AR15 slam fire


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edfardos
November 17, 2013, 04:26 PM
I've had two slam fires in my last 100 rounds (two different outtings). Basically fires twice with a single trigger pull. The AR15 in question has fired roughly 1500 rounds total, with never a glitch.

I recently switched to CCI400 primers since I couldn't find any CCI450(magnum) primers. I've fired 300 of these, and the two slamfires were somewhere between shot 200 and 280.

The two slam fires were also with a new lot of FC brass, and I normally use PMC.

I'm attaching a picture of the two brass involved in this uncommanded double tap. The picture looks exactly like dozens I've seen on the internet. One's an "inny" and ones an "outty".

Any idea what's happening? I'm assuming sensitive primer, or possibly the brass is involved since those are the only variables. The AR15 lower function-checks just fine on the bench. My firing pin puts a pretty good ding in the primer when the bolt closes, just like others I've seen on the internet.

How unsafe is this condition? I still have 350 live rounds with these primers, and a box of 1400 unused primers.
http://sierraglider.com/craiger/slamfire1-crop.jpg


curiously,
-edfardos

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Guilty
November 17, 2013, 05:07 PM
I would tend to first suspect that your finger is hitting the trigger on recoil rather than a slam fire, especially if you have installed a trigger with a lighter pull than a heavy pull battle trigger for example.
If you still suspect a slam fire, maybe check the primer seating depth and make sure that you aren't seating the primers too high.
If you continue to have problems, change to a CCI 41 primer which has a harder cup. A little trial and error testing is in order.

carbine85
November 17, 2013, 05:29 PM
It's best to use harder primers in the AR or any semi-auto with a floating firing pin. Check the seating depth of the primers. The AR isn't known for slam firing. Assuming the trigger group is ok and the firing pin is floating I would suspect the primers.

edfardos
November 17, 2013, 05:31 PM
thanks for the feedback. I'll double check primer seating on the next trip, mark any that are possibly high or flush.

I recall researching the difference between standard and mag primers, and CCI used thicker material for their cups. My current working theory is the new, thinner primers are detonating when the firing pin hits the primer as the bolt closes over the cartridge.

The other wild card is this new lot of commercial FC brass. Is there anything brass might contribute to a slam fire? Everything is full length sized, no different from the last 1500 rounds of PMC I reloaded.

I'll switch back to CCI450/mag primers in the future, but the big question is if my existing 350 live cartridges are safe to discharge. If the firing pin can hit the primer when the bolt closes, it means the rim has already passed over the extractor and it's highly likely the bolt has locked right? What are the odds of an out-of-battery discharge?

thanks again,
-edfardos

243winxb
November 17, 2013, 05:31 PM
Always load a round from the magazine. What are the odds of an out-of-battery discharge? Not with an M16 type, unless maybe a broken firing pin?? Yes for the M1 & M14 .

TBH
November 17, 2013, 05:35 PM
I agree with Guilty. I have a Jewel trigger and set it for 2.5#. I have had several double taps. They would be fun if you were expecting them, but not by surprise.

I am now set at a nice crisp 4#. You need enough weight to make your trigger finger pull through. Now if you have a stock creepy, 6-7# trigger, then it may be the primers. I use only CCI 450. I am sure deep down you already know if the 400s are slam firing, you need to pull the rest of them. Don't feel alone, I loaded 400 69g SMKs and twice had powder hang up in my powder measure funnel. Dillion 550b, N140. Not sure why, but I placed an order at Midway for a puller.

Good luck!

ole farmerbuck
November 17, 2013, 05:35 PM
Can the firing pin be gummed up causing this?

blarby
November 17, 2013, 05:54 PM
I would like Slamfire1's opinion.

Maybe its a trick of the lighting on that pic, but my primers still set deeper than that after firing.


With that said- when you are having malfunctions, its best to investigate fully before you consider anything "safe".

I would have stopped after the 1st double.


Its entirely possible you are getting a recoil/trigger doubletap.... Its entirely possible you are not.

I've never had a slam using cci400's, but you do hear about them using Federal smalls enough that I wont use them in this application.



Given that we're into the cold weather months, that can't be ruled out as a failure point yet- but that would be more lubricant binding on your firing pin, unless i'm mistaken Edit- you'd have more than a lube issue. Gloves and the trigger have caused this on cold days- i've seen it ! That was a fun end of a magazine.....


I think we've hit on most of the common cause/variables. Now its time to find out which one !

#1- check the firing pin for movement/non movment due to gumming. If you play with your bolt/carrier assy when you take it out, you could rule this AND serious mechanical failure right out- see havys post below. You can simulate that on a bench.
#2- weight check your trigger pull
#3- fire some factory ammo and see if you get a duplicate

MEHavey
November 17, 2013, 06:04 PM
I wager you have doubling (probably recoil/trigger-finger bump) and/or the disconnector failing (to capture the hammer until the trigger is reset). The hammer then rides the bolt home.

Luckily, the AR15 design does not allow to firing pin to protrude from the bolt face until the lugs are pretty much locked -- hence danger from a classic Garand-type (and true) Slamfire is vanishly small.

edfardos
November 17, 2013, 06:23 PM
wow - great info guys. Just to touch on the points:

1) Trigger group function-checks perfectly on the bench (disconnector holds).
2) No lube on the firing pin other than some oily fingers putting it in.
3) It never did this in the last 2000 rounds with CCI450-mag primers
4) Trigger is a very heavy, "stock creepy" S&W trigger group
5) The extruded primer bump indicates a detonation with no hammer behind the pin?
6) I've tried to bump fire it for fun in the past... poorly.
7) First slam fire was off of bags (slow pull), second was off knee (fast pull)

Two variables are the non-mag primers and this new FC brass.

first 2000 were mag-primers with PMC brass -- no slam fires
next 100-200 were non-mag primers with PMC brass -- no slam fires
next 201-300 were non-mag primers with FC brass -- slam fires on #225 and #275

AR15 is detail stripped/cleaned every 50 rounds. I tripple checked the firing pin, good dome on tip, amazingly straight, slides with ease, no excessive grease, no flakes in the tunnel/bolt.

For posterity, the lot# of these primers is "B11U". and I have 1400 to trade, if you have a bolt-action small-rifle :)

I'm still leaning towards the non-mag CCI400 primers, but I really want you guys to challenge me and think of additional alternative causes. Especially if we can find a real safety issue here. I'll shoot some of my reserve stock with cci450 mag primers for now.

thanks again,
-edfardos

243winxb
November 17, 2013, 06:38 PM
This photo shows that the hammer was not dropped and in contact with the firing pin. The slide closing at too high a velocity will let the inertia firing pin hit the primer. A weak ejector spring will not slow the bolt, as much as it should. http://i338.photobucket.com/albums/n420/joe1944usa/SlamfireAR_02.jpg

DC_art
November 17, 2013, 07:16 PM
I recall researching the difference between standard and mag primers, and CCI used thicker material for their cups. My current working theory is the new, thinner primers are detonating when the firing pin hits the primer as the bolt closes over the cartridge.

I think you missing the intended direction of using a harder primer. Using a CCI 450 (or any SR Magnum) primer would be an entirely different load. The CCI 41 should be functionally equivalent to the CCI 400 (same load) but with a harder cup.

rcmodel
November 17, 2013, 07:23 PM
first 2000 were mag-primers with PMC brass -- no slam fires
next 100-200 were non-mag primers with PMC brass -- no slam fires
next 201-300 were non-mag primers with FC brass -- slam fires on #225 and #275 Make sure you remove all the military primer crimp before seating primers.

I ran into that doubling problem years ago with my Colt when I was smashing in CCI 400's with my loading press, even though they didn't want to go.

Smashed primers are more sensitive then the same primers seated with a normal amount of force.

I have never again had a double after I started swaging primer pocket crimps, and seating with an RCBS hand priming tool so I could better feel what was going on.

rc

edfardos
November 17, 2013, 07:38 PM
Weak ejector spring? You've got me interested DC_art.

The ejector spring is the cylinder that compresses behind the rim of the cartridge right? It's all I can do to compress this with a thumbnail. And this is not to be confused with the extractor spring (with rubber o-ring). I would expect both of these springs to slow the closing of the bolt. You've given me something to think about - thanks.

rcmodel -- you've never been wrong about anything on this forum -- ever :).
I give primer seating some serious muscle on my rcbs-pro-2000. To the point where I've been wondering if I'm damaging the primer. But that applies to my previous 2000 flawless rounds as well. Maybe I'm damaging the CCI400 (non-mag) primers during seating... again, something to think about, but w/o the muscle, I get proud (high) primers from time to time.

243winxb: great picture. That's exactly what I'm seeing. I think we're all agreed (agreeing) it's an inertial strike and not a hammer strike? That explains the extruded primers.

My plan is to shoot some of my old-stock cci450 mag-primers and see if I can replicate the slam fire, which will point at the firearm. Then I'll try some of the newer CCI400 non-mag primers and see if it comes back. That should be a sufficient test. At this point I think the change in brass (FC) is probably a coincidence.


more to think about, thanks,
-edfardos

rcmodel
November 17, 2013, 07:43 PM
I think the Fed brass had more remaining primer crimp left in it then the other two brands.

Smashing primers in past a crimp!
That's what does it I tell ya!!

rc

edfardos
November 17, 2013, 07:44 PM
DC_Art, I'm using H335, which calls for a magnum primer in the Speer manual (but no other manual). It's technically a ball powder. Accuracy results have been optimal with the mag primer (and just fine with the non-mag primer, except for the slam fire). I load nowhere near max (23.5grains under 55grain hornady).

--edfardos

edfardos
November 17, 2013, 07:46 PM
rcmodel - this is commercial brass - no crimp. I can't get my rcbs pro2000 to reliably prime de-crimped brass (1 in 12 goes in at an angle, no matter how much crimp i remove). I have bags of unused crimped brass in the garage :/.... I really like your theory on over cramming primers into pockets. I'll try with less force, yet make sure they're still not high.

--edfardos

DC_art
November 17, 2013, 07:49 PM
Edfardos,

I'm not the one discussing the ejector spring. I'm just cautioning you about substituting in a magnum primer. That would require a different load. That would be a whole new variable in the equation you're trying to solve.

Art

rcmodel
November 17, 2013, 07:55 PM
I can't get my rcbs pro2000 to reliably prime de-crimped brass Then you need to up-grade to a better method of priming.

My RCBS hand priming tool has worked flawlessly for a lot of years.

You just can't beat the 'feel' and control they give you with press priming.

rc

243winxb
November 17, 2013, 08:04 PM
I'm assuming sensitive primer (CCI 400) You would be correct. Problem solved. :D

Walkalong
November 17, 2013, 08:05 PM
I have never had a slamfire in an AR using various primers. Granted, I do not shoot the number of rounds some of ya'll do. I did have a RRA two stage trigger start doubling. I replaced it and the problem went away. Seating primers below flush is paramount.

This photo shows that the hammer was not dropped and in contact with the firing pin. How does it show that?

243winxb
November 17, 2013, 08:09 PM
How does it show that?
2 on left, primer flowed into the firing pin channel. The firing pin nose was not contacting the primer. The hammer was still cocked.

edfardos
November 17, 2013, 08:12 PM
oh, and for full disclosure, i've been proving the new Magpul 10-round magazines, which were definitely in play during the first slam fire, and possibly involved in the second. Yah, I'm from California, and have been patiently waiting for Magpul to produce a real 10-round mag.

--edfardos

Walkalong
November 17, 2013, 08:17 PM
2 on left, primer flowed into the firing pin channel. The firing pin nose was not contacting the primer. The hammer was still cocked.
Makes sense, even though a poor firing pin fit in the FP channel can cause the primer to look like the ones on the left. But that isn't the problem judging by the other cases fired in the same rifle. Interesting. Thanks.

IMtheNRA
November 17, 2013, 08:20 PM
That's the reason they have CCI-41 primers. Magnum and bench-rest primers are also thicker than standard CCI-SR primers.

A couple of years ago, I had a slam fire when using up a box of left-over CCI-SR primers and slam fired primer looked just like yours. It's not a big deal when plinking on the range, but could get me DQ'd from a match. Been using bench-rest primers ever since.

Had you doubled by accidentally pulling the trigger, regardless of the aftermarket trigger brand, the primer would look just like the rest of your normally fired primers.

Regarding high-primers, I think that's less likely to cause a slam fire than a misfire, since much of the firing pin energy would be used to seat the primer and crush the priming compound between the cup and anvil. Then, it would have to retain enough energy to activate the primer. Seems like a long shot to me.

rcmodel
November 17, 2013, 08:22 PM
(CCI 400) You would be correct. Problem solved.CCI #400 is about all I have used in AR'15s and Mini-14's for going on 44 years.

That ain't the problem, unless you smash them in.

rc

ole farmerbuck
November 17, 2013, 08:28 PM
Just shoot a couple of rounds then eject the loaded round from the chamber and see if there is a firing pin mark on the primer.
(hope nobody already said this)

rcmodel
November 17, 2013, 08:32 PM
In my experience, there should be a firing pin mark on every primer that has been chambered but not fired.

Military M-16's do it with mil-spec ammo, commercial AR-15's do it with commercial & reloaded ammo too.
They all do it.

It's just the nature of the floating firing pin to ding every primer when the round slams home and the bolt locks and allows the firing pin to bounce off the primer.

It will not fire it, but it always leaves a small mark.

rc

ole farmerbuck
November 17, 2013, 08:38 PM
I see.

243winxb
November 17, 2013, 08:43 PM
For posterity, the lot# of these primers is "B11U". and I have 1400 to trade, if you have a bolt-action small-rifle My CCI 400 primers (lot No. H05Q) flow in my Savage axis with mid-range loads. Primer sensitivity may change from lot to lot? Rem 7 1/2 show no flow. It's just the nature of the floating firing pin to ding every primer when the round slams home and the bolt locks and allows the firing pin to bounce off the primer.
Very True. http://i338.photobucket.com/albums/n420/joe1944usa/M16A1%20Carbine/th_M16A1Carbine007.jpg (http://s338.photobucket.com/user/joe1944usa/media/M16A1%20Carbine/M16A1Carbine007.jpg.html)

edfardos
November 17, 2013, 08:49 PM
Yup, significant ding is in the primer after the bolt closes. Always has been. But with these CCI400 (non-mag) primers, that ding is sufficient to detonate the primer compound, especially if what RCmodel is saying, with me making the primer super-sensitive by inserting it with too much force.

Editorial: CCI might be having quality control issues too. I've seen a few thousandths difference in their cup height between lots. My first box of CCI450's took an amazing amount of force just to seat flush. Subsequent lots were easy, and measured shorter.

--edfardos

SlamFire1
November 17, 2013, 10:17 PM
I don't believe the idea that you can make a primer super sensitive through seating, this is something that is unsupported by data. If anything, it will crack the primer cake and make a dud primer. You will run into a lot of people who do not accept the idea that the inertial impact of firing pin could set off a primer. The AR15 actually went through troop trials and was in general issue before a slamfire pattern was fired out. As usual, the Armed Services deigned there was anything wrong with their rifle, blaming ammunition manufacturer's for "high primers", but in the end, what was found that there was something wrong with their rifle and their ammunition specification:


Report of the M16 Rifle Review Panel. Volume 5, Appendix 4. Ammunition Development Programhttp://www.dtic.mil/dtic/


Primer Sensitivity

Initial Specifications. Ammunition specifications established by the Air Force on 24 January 1963 provided for quality control against cocked, inverted, loose, and nicked primers. The specifications further provided for inspection and test of waterproofing
and the crimp of primers. However, the specifications did not provide for specific limitations on primer sensitivity for 5.56mm ammunition.-

Development. At the first meeting of the Technical Coordinating Committee on 26 March 1963,16 / the Air Force representatives submitted a list of reported ammunition deficiencies, which included "high primers" and "primers too sensitive". It was agreed that Frankford Arsenal would investigate the matter and recommend corrective action.

One of the malfunctions reported by the Air Force was the premature firing of cartridges that occurred upon initial charging of the M16 rifle with a cartridge from the magazine, or upon singleloading of a cartridge directly into the chamber, or when two rounds were fired at one trigger pull during semiautomatic fire.

This malfunction was attributed to "high" or protruding primers, although the tests did not confirm this theory..

However, analysis indicates that if high primers caused the premature firing, the firing should have occurred upon impact of the bolt face with the protruding primer. At this point in the weapon cycle, the bolt head would not. have been rotated to the locked position by action of the cam pin and carrier. Had firing occurred with the bolt in the unlocked position, it would have resulted in a blow back and would not have been undetected. No such disruptions were reported . Since premature firing occurred after bolt-locking, it must have coincided in time with the impact of the bolt carrier against the bolt head. At the instant of impact, the "free floating" firing pin is moving at the velocity of the bolt carrier. The kinetic energy of the pin must be dissipated by such frictional forces as it encounters in the forward movement, and, finally, in impact of the firing pin tip with the primer of the chambered cartridge. This premise was confirmed by the visible indentation appearing on cartridges which were chambered by the mechanism and extracted unfired.

As CCI has stated, high primers are the most common cause of misfires in the article Mysteries And Misconceptions Of The All-Important Primer http://www.shootingtimes.com/2011/01/04/ammunition_st_mamotaip_200909/ because the anvil has to be firmly seated on something and the primer cake pushed into the anvil. Not saying that something weird could happen in a tight pocket or a pocket which the crimp was not removed, certainly a shallow pocket could produce the conditions necessary for a high primer to ignite, which is a firmly seated anvil and the primer cake pushed into the anvil, but since these were not here, I don't believe these are the causes.

Slamfire deniers don't recognize that primer sensitivity varies by lot and each individual primer varies in sensitivity. To them, primers are all like the same, all act the same, and they basically ignore primer sensitivity. They are very consistent in holding that primers are a non issue and that all slamfires are caused by mechanical means and user misconduct. They learned this from an Ordnance Employee who wrote for the American Rifleman. In the article he wrote, the only allowed causes for slamfires were high primers and your worn out receiver bridge. This was back in the day when the only semi autos on the market in quantity were M1a's and M1 Garands, of course , this fails for AR15's which don't have a receiver bridge. It is interesting to note that this author was a leading participant in the AR15 slamfire investigation in the 60's but when it came to slamfires and the Ordnance Department designed M1 and M14, primer sensitivity has nothing to do with anything.

Still, at the time, the Ordnance Department calculated they wanted a primer sensitivity that gave a 1:10 million chance of a slamfire for the AR15. People win lotteries every month even though the odds are 1:100 million.

Commercial primers are on the average more sensitive than mil spec primers and you would expect the more sensitive the primer the greater the chance of a slamfire. However, and this must be understood, this weapon and any weapon with a free floating firing pin can slamfire due to firing pin inertia even with mil spec primers.

This chart came from a DTIC presentation and you can see that given a certain dryness, probability of ignition varies, and varies by impact. At certain impact energy levels the probability of ignition is close to 100%, but at other energy levels, sometimes it goes off, sometimes it does not. Incidentally this is the military primer mix.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/Primer%20Sensitivity/ImpactEnergyofMilSpecPrimercompositionV1.jpg (http://smg.photobucket.com/user/SlamFire/media/Reloading/Primer%20Sensitivity/ImpactEnergyofMilSpecPrimercompositionV1.jpg.html)

Different primer compositions have different ignition curves. Red phosphorous is a different primer technology, but you can see how the ignition curves are different. Primer cake is a mixture and the % of components will always vary so you would expect that some batches of primers are going to be a little more sensitive or a little less sensitive. We all have had dud primers, and extra insensitive primer, but slamfire deniers will not admit that there is such a thing as an extra sensitive primer.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/Primer%20Sensitivity/RedPhosphorousprimersensitivity.jpg (http://smg.photobucket.com/user/SlamFire/media/Reloading/Primer%20Sensitivity/RedPhosphorousprimersensitivity.jpg.html)

Federal makes the most sensitive primer composition and primers, but Federal finally reacted to the many AR15 slamfires by issuing their mil spec primer. According to this, they did not change the mix, but they made the primer cup thicker, which deadens the firing pin blow. We should encourage Federal to make their military large rifle primer line available to the public and reduce the number of slamfires in Garands and M1a's.

http://bulletin.accurateshooter.com/2011/09/new-federal-gold-medal-match-primers-for-ars/

September 11th, 2011
New Federal Gold Medal Match Primers for ARs
Federal Ammunition has released a new type of small rifle match primer optimized for AR15s and similar semi-automatic rifles. The new Gold Medal® AR Match Primers, designated GM205MAR, have harder primer cups than the popular Federal 205M match primers. The harder cup is designed to perform better in semi-automatic actions that use free-floating firing pins. A Federal spokesman said that Federal’s “normal” 205M primers were not ideal for use in firearms, such as ARs, with free floating firing pins. Hence Federal designed the new GM205MAR primers. These are available now from major vendors such as Midsouth Shooters Supply, which offers the new GM205MAR primers for $35.22 per thousand.




Here's the skinny on the Federal GM205MAR primer.
http://68forums.com/forums/showthread.php?32572-Here-s-the-skinny-on-the-Federal-GM205MAR-primer

My friend at RCBS contacted the expert at Federal, and this is what he was told:

Mix is the same as in the standard small rifle primer. The primer cup is thicker, as is the anvil. The thicker cup and anvil “should” desensitize the primer a bit, and “lessen” the chance of a slam-fire. Federal primers are in general, more sensitive than CCI and less tolerant of firing pin blows during loading into the chambers of the M1 Garand, M1-A, and AR platforms.
I hope this helps shed some light.

This is an interesting comment on the best type of primers to use in AR's:
Milspec primers for AR's not necessary?? See what the manufacturers have to say.

http://www.atgreloading.com/t1157-milspec-primers-for-ar-s-not-necessary-see-what-the-manufacturers-have-to-say

by RemMan700 on Tue Aug 30, 2011 9:43 pm
Most people think that the CCI #41 is the only safe primer for fire arms with free floating firing pins such as the AR-15. I contacted several manufacturers to see what they had to say on the subject and if their primers were ok with these types of firearms.

CCI:
Hello,
Could you please tell me what the difference is between the CCI 400 primer and the CCI 41 primer? Does the 41 primer have a thicker/harder cup and less sensitive priming compound then the 400 primer?

Response:
A CCI 400 is our 'standard strength' of small rifle primer.

A CCI #41 primer is a 'magnum' strength of primer, equivalent to our CCI 450 Small Magnum rifle primer, ballistically. The #41 primer also has a feature to help lessen the chance of a slam fire in semi-auto types of firearms. This feature is that there is more distance between the tip of the anvil and the bottom of the cup, creating a slightly less sensitive primer. The #41 primer also has a thicker bottom on the cup than the CCI 400 primer.

Linda Olin
CCI/Speer Technical Services
2299 Snake River Ave.
Lewiston, ID 83501

Now, my first thought on reading this thread was that your doubles were due to bump firing. Back in the day when everyone shot with a tight sling, you just did not have bump fires. Now most shooters are shooting using sandbags and a bench rest and bump fires are very frequent. However, your primer picture makes me think that you did have a firing pin initiated slamfire especially by the weird donut on one primer. I am seeing more and more AR15 slamfire primers with that donut shape. For some reason, Garands and M1a slamfire rounds don't have this feature, they look like a normal indention. Don't know why.

Conditions that could cause an out of battery slamfire in a AR15 is a shallow primer pocket with a properly seated primer sticking high above the case head, a broken firing pin sticking through the bolt face, or an over long firing pin sticking through the bolt face. That is about the range of possibilities that I can think of.

I have never heard or seen a busted AR15 firing pin, though not saying it could not happen, and an over long firing pin could happen, but have never seen one, so as long as you ensure that your primers are properly seated below the case head, you are not going to have an out of battery slamfire in this mechanism. Only in battery slamfires.

I think is that you have a batch of standard CCI primers that are more sensitive than usual. I would not use this batch in a semi auto even though an inbattery slamfire will not blow up the rifle or you, but, a bullet zinging down range because your rifle unexpectedly went off could hurt someone else.

edfardos
November 17, 2013, 10:41 PM
SlamFire1, wow, just wow. You've obviously chosen the right nicname on this forum as well. I agree with all your points. My biggest concern was an out of battery slam fire, but as you, and others have indicated, that's highly unlikely. I tend to agree i have a batch of sensitive primers. I'll likely fire my remaining live rounds and sell my unused primers to bolt-action friends. I'll be switching back to CCI450 (mag) primers when I can find'm. While I'm sure CCI400's have worked in many AR15's for years, there's a clear indication I have a sensitive batch. I emailed CCI to this effect as well. I also use a deserted area of the National forest, far from anyone and anything, but to be honest that second shot is right behind the first, it happens that fast.

Great science guys - this is a huge help.

--edfardos

blarby
November 17, 2013, 11:00 PM
SlamFire1, wow, just wow.


And thats why I was waiting for his response :D

Joe's
November 18, 2013, 07:52 AM
SlamFire1, Excellent write up. I too think staying with 450's is the way to eliminate t'he OP's experience.
One question though, wouldn't the OP's problem be better described as a Double Tap rather than a Slam Fire?

Be Well,
Joe's

genebofunk
November 18, 2013, 09:06 AM
I had a batch of CCI primers that were sensitive too. I had several slam fires out of one lot. One happened when I inserted a magazine and hit the bolt release. It put a decent sized hole in the concrete 2 feet in front of me. It happens. As a result I always keep the barrel pointed at the berm/backstop when I charge the first round.

GW Staar
November 18, 2013, 11:01 AM
Then you need to up-grade to a better method of priming.

My RCBS hand priming tool has worked flawlessly for a lot of years.

You just can't beat the 'feel' and control they give you with press priming.

rc

If you are going to prime using any progressive press, you have to make sure you've not only got the crimp out, but that you have a decent presentation to the pocket. That means a rounded or chamfered entry that won't catch an edge and crumple the primer going in. There's nothing worse when loading progressively than having stoppages due to primers not feeding right....and no press is immune when primer pockets are suspect.

For trouble-free feeding either ream with a reamer that rounds the edge or swage and then touching the swaged pocket to a reamer for a half second in a Trim Mate (while doing uniforming and flash hole deburring operations)

If you look at commercial brass, you'll notice they all have rounded entry.

Since the O.P. uses a Pro 2000, I'd suggest uniforming pockets so that you can use the depth stop....that's the only way you can be ensured of pockets set the same depth using the press.....it makes up for the lack of feel you can only get from a hand primer. I still use a hand primer, for odd balls I don't load progressively, and I use one to prime a first case to the proper depth....put that case in the press in #2 and use it to set the depth screw to make quick work of the rest of the batch.

I had one slamfire 2 years ago (Remington R25/DPMS AR10 clone), and that was before I got decrimping military brass to be used on the progressive figured out. (in the middle of the learning curve with a new press) The reason for that one was a high primer....one of two in a batch of 100. The high primer was caused by my swager shearing off a thin ring of brass in the crimp and depositing it into the bottom of the primer hole......Then when I uniformed the hole the ring of brass just spun preventing it from cutting to the target depth.

I found a similar ring of brass in the pocket of the 2nd high primer in the batch. (that round was un-shot but taken apart for inspection) Moral of the story is if you uniform and it doesn't seem to be cutting, check for a brass ring.

One more note for the O.P. if he uses a swager. Using a Trim Mate, (or drill) you can have trouble with the pocket catching on the uniformer and wanting to yank it out of your hand. That's another sign of too sharp a presentation to the pocket. Touch the pocket to the reamer first, then uniform the pocket with no trouble at all.

edfardos
November 18, 2013, 11:10 AM
If you are going to prime using any progressive press, you have to make sure you've not only got the crimp out, but that you have a decent presentation to the pocket. That means a rounded or chamfered entry that won't catch an edge.

I accomplish that by either reaming with a reamer that rounds the edge or swaging and then touching the pocket to a reamer for a half second in a Trim Mate (while doing uniforming and flash hole deburring operations)

If you look at commercial brass, you'll notice they all have rounded entry.

Since the O.P. uses a Pro 2000, I'd suggest uniforming pockets so that you can use the depth stop....that's the only way you can be ensured of pockets set the same depth using the press.....makes up for the lack of feel you can only get from a hand primer.
GWStaar, I disable the depth stop and seat by feel on the rcbspro2000. The variances in rim thickness will allow high primers even as the press hits the stop. I use the stop in 40S&W, because it's easy to crush/deform small pistol primers, and for some reason 40's seem to seat deep easily. I think RCmodel is right about making sensitive primers by using too much force, but my force hasn't changed for the last 2000 rounds and I'm seeing slamfires with a new lot of CCI400's. Looking at my loading logs, it would appear I used CCI400 long ago, w/o problems. I'm still thinking I have a bad lot. The only other variable is this FC brass, but I can't make a connection to that at this time.

1300 CCI400 primers for sale! $45, Auburn/Sacramento area, bolt action users only please :).

thanks again for all the info. I feel more comfortable shooting the rest of these since the AR15 can't really slam-fire out-of-battery unless the primer is high (which I'll be double checking before I go to the range).

cool,
-edfardos

GW Staar
November 18, 2013, 11:53 AM
GWStaar, I disable the depth stop and seat by feel on the rcbspro2000. The variances in rim thickness will allow high primers even as the press hits the stop. ............

-edfardos

Rims don't vary that much. If you set the stop to seat .007 with a "thin" rim and they vary .002, worse case is .005 below flush. Still plenty deep. But if you can "feel" them in with the press, go for it.:) I can't...too old I guess.

ArchAngelCD
November 18, 2013, 03:35 PM
I think you missing the intended direction of using a harder primer. Using a CCI 450 (or any SR Magnum) primer would be an entirely different load. The CCI 41 should be functionally equivalent to the CCI 400 (same load) but with a harder cup.
That statement is completely incorrect. The NATO rated CCI#41 primers are magnum strength primers without a doubt and that is directly from CCI, not a guess. The information is at the bottom of the linked page and other spots on their site too.
http://cci-ammunition.com/products/primers/primer_chart.htm
The 41's and 34's contain Magnum priming mix and should be treated as such.

I have used a handful of different primers in AR ammo and all have worked for me without incident. In order of preference these are the primers I have used: CCI #41, CCI-450, Remington 7 1/2 and CCI-400.

When loading .223 ammo meant for a bolt action rifle I use either CCI-400 primers or CCI BR-4 primers.

edfardos
November 18, 2013, 04:49 PM
CCI replied to my inquiry the next day!
.......................................................

"the CCI 400 primer has a standard cup and the CCI-450 primer has a thick cup, this is the difference and if slam fires are a concern then you should be using the CCI #41 primer. It has a thick cup magnum priming charge and an anvil angle change to prevent slam fires. "

Make Every Shot Count!
Justin M.
CCI/Speer

DC_art
November 18, 2013, 10:49 PM
That statement is completely incorrect

ArchAngelCD,

With no * or other flag, I missed the note at the bottom of the page. I consulted that page but completely missed it. Not a good way to put that somewhat important information out there.

Lesson learned. Thanks

Humbly,

Art

ArchAngelCD
November 19, 2013, 06:25 AM
Art,
No reason to be contrite. This isn't a competition, we are all in this together. It doesn't matter who comes up the the answer as long as in the end we all get the correct information. :)

Welcome to the forum...

243winxb
November 20, 2013, 08:02 AM
next 100-200 were non-mag primers with PMC brass -- no slam fires
next 201-300 were non-mag primers with FC brass -- slam fires on #225 and #275
I wonder if head clearance is a factor when using sensitive primers ?? When comparing head to datum of both lots of ammo, would a difference of .010" have an effect? If the slam fired rounds only had .002" head clearance, would the primer be struck by the inertia firing pin with more force? The rounds with .010" head clearance would have more slop in the chamber. A light tap from the pin may move the round forward in the chamber, not causing a slam fire? But maybe the extractor would keep the round from moving forward? This is with all primers seated correctly, about .004" below the case head. Just thinking out loud.

edfardos
November 25, 2013, 04:20 PM
Good ideas, but I would think the rather powerful ejector spring would keep the round seated as far forward as possible, either against the extractor, or against the shoulder whichever comes first.

Fwiw, I fired another 50 of the "suspect" rounds, with zero slamfires. I'm on target when I close the slide in any event. Probably a good habbit in general.

edfardos
(OP)

Dolph92
December 2, 2013, 12:04 AM
I had this happening with my disconnect. If I pulled the trigger and held it bottomed out then the disconnect would work fine. If I pulled the trigger really really slow and careful like I was shooting for accuracy I could hold the trigger half way and the disconnect wouldn't catch. I had it pump 3-4 off at a time while figuring it all out.

sinbad339
December 2, 2013, 09:27 PM
I had this happening with my disconnect. If I pulled the trigger and held it bottomed out then the disconnect would work fine. If I pulled the trigger really really slow and careful like I was shooting for accuracy I could hold the trigger half way and the disconnect wouldn't catch. I had it pump 3-4 off at a time while figuring it all out.
This isn't the first mention of a failure of the disconnector to cause a slam fire, but I understood that the AR15 bolt will not allow the hammer to follow the bolt home all the way; instead it is "captured" with the bolt not completely closed. The intent is to prevent simple conversion to full auto (although not select fire) of an AR15. Can someone verify this?

rcmodel
December 2, 2013, 09:33 PM
The way all AR-15's/M-16's work is, the bolt slides in and out of the bolt carrier.

It is only locked shut at full foreword travel of the bolt carrier.
As the bolt carrier telescopes over the bolt, the cam pin rotates the bolt into full lock-up in the barrel extension.

At all other times?

The firing pin is too short to reach the primer until the bolt carrier has already locked the bolt shut.

Even IF the hammer could hit the firing pin before the bolt is locked?
It is too short to reach the primer until the bolt is rotated into full lock-up by the bolt carrier & cam pin.

In a full-auto M-16, the hammer is tripped (by an unnamed part) of the trigger group AFTER the bolt is fully locked by the carrier.

If the hammer simply followed the bolt carrier down, it would not have enough energy left to fire the primer.

rc

HisStigness
December 2, 2013, 09:43 PM
I was told that ARs shooting 300blk are susceptible to slam fires so I have been using cheap tula primers with a hard cup. Does anybody know why 300blk would be more likely to slam fire?

sinbad339
December 2, 2013, 09:52 PM
The way all AR-15's/M-16's work is, the bolt slides in and out of the bolt carrier.

It is only locked shut at full foreword travel of the bolt carrier.
As the bolt carrier telescopes over the bolt, the cam pin rotates the bolt into full lock-up in the barrel extension.

At all other times?

The firing pin is too short to reach the primer until the bolt carrier has already locked the bolt shut.

Even IF the hammer could hit the firing pin before the bolt is locked?
It is too short to reach the primer until the bolt is rotated into full lock-up by the bolt carrier & cam pin.

In a full-auto M-16, the hammer is tripped (by an unnamed part) of the trigger group AFTER the bolt is fully locked by the carrier.

If the hammer simply followed the bolt carrier down, it would not have enough energy left to fire the primer.

rc
rc,

I understand about an AR15/M16 not firing out of battery, but I also read where the AR15 bolt is designed to "catch" the hammer if it is riding the carrier forward.

"Another difference [between the M16 and AR15] in the bolt carriers is the additional metal removed on the underside to expose the collar of the firing pin. This is intended to catch the hammer and prevent firing if the carrier is not fully forward when the hammer releases. This occurs if the hammer is "riding" the carrier back (i.e. no auto sear is holding back the hammer). On the M16 bolt carriers, the firing pin collar is not exposed."

http://i254.photobucket.com/albums/hh115/sinbad339/boltCarrier2.gif (http://s254.photobucket.com/user/sinbad339/media/boltCarrier2.gif.html)

heavydluxe
December 2, 2013, 11:45 PM
rcmodel - this is commercial brass - no crimp.

I'm *very* new at this reloading thing, but... The only caliber I'm reloading is 223, and I've seen a lot of Federal 223 (commercial) once fired brass.

The stuff I've seen most definitely *does* have a crimp in it. I started a whole thread about a primer I half-smashed into a case and couldn't get it out of my hand primer. My best guess is that some (though not all) Federal commercial 223 is using LC seconds or something with the commercial headstamp.

YMMV substantially, and take this post with the requisite grain of salt.

Regular Joe
December 2, 2013, 11:59 PM
Just 2 points here-
On another forum, someone found the primer cup thicknesses for all of the popular brands. I believe that CCI 400 was just .018", and known to be "soft". Most of the others are .020", but Rem. 6 1/2 is made of a softer material, and has a note on the box that warns against high intensity loads.
Winchester standard had the thickest of all standard cups, at .025", and indeed the CCI #41 were thicker than that.
Second point- If you load anything that uses small pistol primers, you might use up the 400's in that. I bought 4,000 of the Rem. 6 1/2's before I knew about the high pressure warning. I thought I was stuck with primers I couldn't use, until I tried them in 9mm. My Glocks light 'em just fine, so they get used in my range loads.
You're on the money about using up the rest of your loaded ammo. It's so simple to just close the bolt after you have the rifle aimed down range. That's how I do it anyway. If a slamfire happens while the rifle is aimed at the target, it doesn't matter. Otherwise, normal safety procedure precludes any danger. ie: You never position yourself in front of a rifle that doesn't have the bolt open and magazine removed.

Regular Joe
December 3, 2013, 12:04 AM
heavydluxe- I believe that the Fed. brass you see is all from the "cheap" military load that is sold in bulk 100 packs. I haven't seen this in print, but I believe that the Fed. plant just runs with the mil. brass in case the Fed. source is needed in a surprise conflict. That way, nothing has to change but where it gets shipped to.

heavydluxe
December 3, 2013, 02:07 PM
heavydluxe- I believe that the Fed. brass you see is all from the "cheap" military load that is sold in bulk 100 packs. I haven't seen this in print, but I believe that the Fed. plant just runs with the mil. brass in case the Fed. source is needed in a surprise conflict. That way, nothing has to change but where it gets shipped to.

Which makes total sense... I just went into this reloading adventure with the errant fact that "all .223 brass (as opposed to 5.56) is not crimped". I was sorely disappointed. :)

Speedster00
December 4, 2013, 02:15 PM
you guys far surpass my reloading knowledge but what I found in my AR, is that if the primer is not seated completely flush, my bolt wont even close. So in the OP's original statement, my gun wont even fire a reload that's primer isn't flush. So now I check every piece of brass and use a counter sink bit if necessary to smooth out the primer pocket and remove any crimps.

SlamFire1
December 5, 2013, 04:50 PM
If the hammer simply followed the bolt carrier down, it would not have enough energy left to fire the primer.

Back in the day when the krieger milazzo trigger was the only non military trigger around, shooters who could not get one would stone their military type triggers to get a lighter trigger pull with no creep.

The contact pressures for the military trigger sear surfaces were high, the stoned parts would wear, and you would often hear these rifles going "full auto" as the hammer followed the bolt carrier down.

The Krieger Milazzo trigger also had its peculiarities. There was this adjustment screw that would always work loose. With enough movement the sear would not be held and you see and hear these rifles going full auto on the firing line.

There were enough incidents of doubling with AR's that the NRA match rules had to be changed. When a Garand or M1a doubled, the second and any other subsequent shots went way over the target. According to the rules, the shooter got an alibi. For his great misfortune he was allowed to shoot again so he had ten shots for record. Of the shots on target in the alibi, he got the lowest value ones that made up for the missing shots in the first string. That was the rule and it was a good rule. As a match director, it cut down on arguments on whether the rifle was defective or not. What always happened, in practice, the rifle malfunctioned during the alibi string, the rifle and the shooter left the range unhappy, but not argumentative, once it was proven definitely that the rifle was defective.

However, with 223’s, how do you give the shooter an alibi string if all ten shots are on target? There were great arguments over the refire rules as competitors want to win, and some were trying to game the system in their favor. This great issue was resolved, rule 14.6 says all shots on target count, and 9.6.1(a) says you don't get a refire, and 9.5 "Disabled Rifle" applies.

http://competitions.nra.org/document...R/hpr-book.pdf

RainDodger
December 6, 2013, 12:56 AM
I'm another hand loader that has never had a slam fire. I'd bet dollars to donuts that you had/have a doubling issue. That's a whole different thing, and you're over-thinking the problem. Sort out your trigger group - that's where your problem is.

I had one AR that doubled a couple of times, and it had a trigger group that had been "lightened and smoothed" by a gunsmith (I use the term loosely)... once I put a Geissele trigger in that AR to match my others.. no problem with doubles. Personally, I think too many people jump on the bandwagon and assume their rifle is slam-firing. I think that's a rare occasion.

Joe's
December 6, 2013, 06:42 AM
See post #35,

"wouldn't the OP's problem be better described as a Double Tap rather than a Slam Fire?"


Joe's

Dolph92
December 21, 2013, 04:03 PM
RC no disrespect but I do not agree at all with your statement

If the hammer simply followed the bolt carrier down, it would not have enough energy left to fire the primer.

I know that this can and will happen. if the disconnect is not correct. It may be a hammer spring tougher than it needs to be or it may be that the disconnect is slightly holding the hammer till trigger release but it's something close to this that happened to me.

Regardless we can probably both agree this is an EXTREMELY DANGEROUS condition.

I understand about an AR15/M16 not firing out of battery, but I also read where the AR15 bolt is designed to "catch" the hammer if it is riding the carrier forward.

The disconnect is designed to do that.

http://www.youtube.com/watch?v=NtwhZj1_TlI

At about the 8:45ish mark you can see this process it is an M16 but the concept is the same. Towards the end of this video is the M-16 parts and the functions in automatic.

Here is the cycle of what happens starting with the bolt in battery and the trigger holding the hammer at the trigger sear.

You pull the trigger releasing the lower hammer sear.

The hammer swings forward contacting the firing pin (the firing pin is free floating design in an AR. It has no spring holding the pin off the primer)

Firing pin strikes the primer launching the bullet pressurizing the gas port
the pressure in the gas tube pushes the blot backwards.

The hammer rides the back of the bolt backwards and is caught by the disconnect on the hammers disconnect sear.

The bolt comes forward loading another cartridge.

You release the trigger and the disconnect sear is released and the hammer swings slightly forward and catches on the trigger sear again. (On my rifle I can now hear a click as it catches again on the trigger sear. When the disconnect was not correct it was very very faint if it did catch at all)

The last step is what was wrong on my rifle as the timing between the disconnect sear and the trigger sear was off and I could literally hold the trigger half way and cycle the hammer back and forth by hand with the upper off of course and the hammer would not catch on anything.

The disconnect was a cheap stamped unit and was sloppy and loose and neither the disconnect sear nor the trigger sear would catch the hammer every time.

sinbad339
December 21, 2013, 10:28 PM
I understand about an AR15/M16 not firing out of battery, but I also read where the AR15 bolt is designed to "catch" the hammer if it is riding the carrier forward.

The disconnect is designed to do that.

Yes, of course the disconnector is designed to catch the hammer. I was talking about a hammer following the bolt/bolt-carrier as has been described above due to somne failure of the disconnector. I'm no expert, but was pointing out that I have read that an AR15 carrier is different than an M16 carrier, and the primary difference is a cut to catch a hammer that is following the carrier. One might presume that it is both a safety issue and to prevent someone from trying to turn their AR15 into a full-auto (though not select fire) by defeating or removing the disconnector.

Also, the ATF maintains that "M16 bolt carrier is listed as one of the "registered" items under NFA."

Finally, on another forum, there was a question about Colt and other manufacturers including M16 dcarrier in some of the AR15 they manufacture. One post included a reply from Colt as follows:
Paul said that Colt is shipping the M16 bolt carrier in all their 'Match Target' AR15s. However, he said that the factory was machining the pin slot of said carrier before it the left production area for installation in the designed 'Match Target' rifles. That of course means that the assembly cannot be used as a MG part. He said that all of the 'Match Target' rifles come with the M16 bolt carrier (modified)."
So... it no longer a registered M16 carrier, and can be used in a standard AR15.

All of this is to say that an AR16 bolt carrier is intended to catch a hammer that is following.

Dolph92
December 21, 2013, 11:37 PM
I see what your saying. I will take a look at mine and see what it looks like. I think it's made that if the sears don't catch it follows the bolt but I am not sure. I will look and let ya know what I find.

Dolph92
December 21, 2013, 11:48 PM
Oh I found a good image on this topic.

http://mcb-homis.com/blog/trigger-animation.gif

http://mcb-homis.com/blog/m16animation1ww1.gif

I looked at my bolt I don't see anything that would prevent the hammer from riding the bolt if the disconnect and trigger sear was gone but the question is how do you get the first shot off without it LOL. Or get the gun to stop firing?

243winxb
December 21, 2013, 11:59 PM
The question is, when the hammer is riding/following the carrier/bolt down, will the round be fired? :D

Rushthezeppelin
December 22, 2013, 03:39 AM
Oh I found a good image on this topic.

http://mcb-homis.com/blog/trigger-animation.gif

http://mcb-homis.com/blog/m16animation1ww1.gif

I looked at my bolt I don't see anything that would prevent the hammer from riding the bolt if the disconnect and trigger sear was gone but the question is how do you get the first shot off without it LOL. Or get the gun to stop firing?
Thanks for posting the second illustration especially, I always wondered how a full auto FCG worked (big mechanics buff, guess I inherited it from my grandad who was an engineer for GE)....not that I'm interested in actually attaining one or trying to (illegally) make my own. I've gotten to fire a full auto (and suppressed :D) M16 before at a BYOA demo put on by a silencer manufacturer and those things are plain unwieldy imo (not to mention expensive to attain and expensive to shoot). Full auto uzis are way more fun as you can actually stay on target.

sinbad339
December 22, 2013, 08:54 AM
None of the above animations include the bolt carrier, so they don't address this issue.

This shows the difference between the M16 hammer and the AR15 hammer, another key component to prevent hammer follow from firing the round in the chamber. Note the notch on the top/front of the AR15 hammer that is not present on the M16 hammer.
http://i254.photobucket.com/albums/hh115/sinbad339/hammer.gif (http://s254.photobucket.com/user/sinbad339/media/hammer.gif.html)

The AR15 bolt carriers, with the additional metal removed on the underside, exposes the collar of the firing pin. This is intended to catch the hammer and prevent firing if the carrier is not fully forward when the hammer releases. This occurs if the hammer is "riding" the carrier back (i.e. no auto sear is holding back the hammer). On the M16 bolt carriers, the firing pin collar is not exposed.

243winxb
December 22, 2013, 09:08 AM
Nice copy and paste from AR15.com :D www.photobucket.com/M16A1

Dolph92
December 22, 2013, 09:42 AM
@Sinbad my hammer doesn't have that corner cut out like in that picture. My bolt doesn't have the same cutout either. So that's probably why it was happening to me.

@243 yes I don't like to link directly to other forums and don't know if moderators here approve of it.

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