5.56 nato vs 223 rem. Ar 15

[Keyfer 55]

AR 15 5.56 bolt different than 223 REM. A article I read said not to fire a civilian 223 in a 5.56 because of the floating firing pin could set off the next round because the primers are different .Has anyone experienced this??? I have an AR in 223 REM. I reload for, l have never used any mill. spec primers .

 

[shoobe01]

YMMV.

But... yes, it's absolutely possible. Drop the bolt to load a round. Eject the round. Look at the primer. The AR15 has a floating (no return spring) firing pin. On bolt forward the firing pin will dink into the primer. Always. Every time. And: soft enough primers can actually go off just from loading.

It is not precisely a .223 Rem vs 5.56 thing but a primer spec thing. If yours don't have a problem: great, keep it up. Your primers are hard enough or your firing pin is blunted enough or whatever. Most loaded .223 is also done with hardish primers (AFAIK) because of AR15s, and avoiding liability so you should be safe and do not see this happen much anymore.

But... rule 2 when loading any gun, always. This is a good reminder of why.

 

[Varminterror]

Guys get too worked up about the “pin kiss” on primers. Millions and millions of AR shooters use non-mil-spec primers and nobody gets slam fires.

My guess is that the author of the OP’s article is not familiar with shooting or reloading for the AR.

 

[Ifishsum]

After participating and observing several years worth of highpower matches where almost everyone uses their own handloads, I will say it's rare but it does happen occasionally. Seen it twice but hasn't happened to me yet. I don't use mil-spec primers but I do primarily use CCI450s and BR4s which have a slightly thicker cup. It's pretty easy to mitigate the relatively small risk by always making sure of your muzzle direction before dropping the bolt.

 

[243winxb]

Chambering rounds from the magazine slows the bolt. Less chance of a slam fire.

A "Bob Sled " magazine provides a single shot loading bed or follower to allow the easy loading and firing of single rounds during competition.

 

[MEHavey]

Unlike the Garand-based designs, the AR bolt/carrier design is such that the bolt must be almost completely rotated into battery before the pin can even emerge from the bolt face.

Slamfire possible? Yeah..... but only in a blue moon when the tree frogs are out.
AbsolutelyRuinYourDayOutOfBattery ? Not so much.




Still... a nice 1000/brick of CCI 41s is a great I-love-me XMas present

 

[Ej3]

Guys get too worked up about the “pin kiss” on primers. Millions and millions of AR shooters use non-mil-spec primers and nobody gets slam fires.

I had two slam fires while testing some loads today. They are top two on the left of the attached photo. It also happened yesterday, but I thought maybe I just double tapped it, not realizing what really happened.

Today I was using WC-844 with Hornady 55 gr V-Max bullets, LC brass and WSR primers. I am hoping that this was more a factor of how dirty my bolt carrier group can get when shooting suppressed. I had shot about 80+ rounds yesterday and did not take the time to clean my bolt carrier group, and just ran a bore snake through the barrel before shooting today. It can get filthy very quickly. After the 2nd slam fire I disassembled and cleaned my BCG and the final testing went fine. But I have to admit, it did not help my accuracy, as I was definitely anticipating it happening again.

I had read this article from www.6mmbr.com and noticed this the statement regarding Winchester WSR in semi-autos.

For use in semi-automatics and AR15s, we advise that you stick to CCI and Remington primers. These brands have harder cups and are much less likely to pierce primers. Also, the AR15 has a free-floating firing pin that dents the primer on loading. This creates a risk of slam fires. So you want hard primer cups. The latest generation of Winchester primers, with brass-colored cups, should be avoided for AR15 use.

Since I have about 5000 WSR primers, this makes me a bit concerned from this point forward. I will be more diligent in keeping my BCG clean.

 

[Walkalong]

The old silver (I assume nickle plated) WSR primers were tougher. I still have a few.

 

[Metal God]

Guys get too worked up about the “pin kiss” on primers. Millions and millions of AR shooters use non-mil-spec primers and nobody gets slam fires.

My guess is that the author of the OP’s article is not familiar with shooting or reloading for the AR.

I agree but the real issue "was" the original firing pin on the M-16/AR-15 was much bigger and heavier then the redesigned version we all use now . See photo below to see original style ( top ) compared to modern style ( bottom )



The older style generated more impact force against the primer when chambering a round and did ( rarely ) cause slamfires . The military corrected the issue by lightening the firing pin and requiring harder primer cups as well as a different angle in the anvil inside the prime making them less sensitive . Generally speaking the lighter firing pin was enough to solve the problem . How ever I would not use standard SR Federal primers with a firearm that uses a floating firing pin design . They are known to be more sensitive then other primers . YMMV but mine is gtg


I had two slam fires while testing some loads today.

IMHO that is very unlikely and is more likely do to poor trigger control , especially if you are using a high end trigger that is lighter then most mil-spec triggers or your hammer or disconnect are out of spec .

 

[Varminterror]

I had two slam fires while testing some loads today.

IMHO that is very unlikely and is more likely do to poor trigger control , especially if you are using a high end trigger that is lighter then most mil-spec triggers or your hammer or disconnect are out of spec .

Yup - far more likely doubling on the trigger, not a slam fire.

 

[Ej3]

IMHO that is very unlikely and is more likely do to poor trigger control, especially if you are using a high end trigger that is lighter then most mil-spec triggers or your hammer or disconnect are out of spec .

I would not consider my trigger high end, but it is a POF drop-in-trigger with 4.5 lbs of pull.

When firing, I thought it was a double tap. But when I saw that the rounds did not have fully dimpled primers, I think it was slam firing when a follow-up round was chambered. I could be wrong, but if it was doubling on the trigger and the hammer fell, I would think that the primers would look no different than the others.

 

[Captcurt]

I had two slam fires while testing some loads today. They are top two on the left of the attached photo. It also happened yesterday, but I thought maybe I just double tapped it, not realizing what really happened.

Today I was using WC-844 with Hornady 55 gr V-Max bullets, LC brass and WSR primers. I am hoping that this was more a factor of how dirty my bolt carrier group can get when shooting suppressed. I had shot about 80+ rounds yesterday and did not take the time to clean my bolt carrier group, and just ran a bore snake through the barrel before shooting today. It can get filthy very quickly. After the 2nd slam fire I disassembled and cleaned my BCG and the final testing went fine. But I have to admit, it did not help my accuracy, as I was definitely anticipating it happening again.

I had read this article from www.6mmbr.com and noticed this the statement regarding Winchester WSR in semi-autos.



Since I have about 5000 WSR primers, this makes me a bit concerned from this point forward. I will be more diligent in keeping my BCG clean.

Yep. Winchester primers are pretty soft. I had to go to them when I was loading for a 7mm TCU Contender pistol. CCI's wouldn't go bang. Winchesters would.

 

[Keyfer 55]

The ISO standards for 5.56 nato primers differ from the civilian version 223 Rem.
I read about this a few years ago. 223 Rem
ammo should be assembled with mil-spec
primers or equivalent to avoid slam fire.

 

[Metal God]

I will admit those primers look different then I've seen , maybe ever . That could still be from the trigger control and the hammer dropping just before lock up essentially acting as if the hammer road the BCG home . Not sure only that slamfires now a days are much rarer then most think and doubling is almost always caused by something else .

I personally have had two rifles that appeared to slam fire on me . One was a Factory complete NIB Del-ton ECHO-316 . In that case I was getting doubles and even triples . Upon further inspection and testing I discovered I could cause the "slamfires" by slowly releasing the trigger after the first shot . I sent it back and it was returned with a note saying the disconnect was out of spec so the hammer was riding the BCG home cause the next round to be fired because the firing pin was already sticking out of the hole when the bolt closed . Which is a slamfire but caused by a defect and not a properly functioning firearm . The other was on my National match build that I put a Geisslie high speed NM trigger in . In that case it was all me and my trigger pull that caused some doubles or what appeared to be doubles . Once I started making the conscious effort to pull trough , hold then release . That rifle has never done it again .

I'm not saying it didn't happen to you , only that it's unlikely and is likely something else .

 

[MEHavey]

That defective disconnectors may have resulted in AR slamfires -- but in battery so that the shooter was able to walk away -- is credit to the genius of Gene Stoner.

 

[Slamfire]

A article I read said not to fire a civilian 223 in a 5.56 because of the floating firing pin could set off the next round because the primers are different .Has anyone experienced this???

I have had them and seen them. Others I shoot with have had them.

It used to be that you could load your rifle on the shooting stool, during the standing stage of NRA Highpower. This was not a problem with a M1a as you pressed a round into the magazine, tripped the bolt, and the muzzle was pointing skyward when you did this. Never heard or saw a M1a slamfire during the standing stage. (Slamfires occurred prone and sitting though!) However, once the AR took over the firing line you saw shooters placing the muzzle of their AR on their shooting stool, dropping a round in the chamber, then hitting the bolt release. The little extra speed that gravity gave to the bolt caused enough slamfires through the shooting stool that the NRA forbid loading your rifle on the stool.

I used to collect slamfire incidents.

AR15 Slamfires



AR15 slamfire with Winchester primers.



http://www.thehighroad.org/showthread.php?p=4627417



Occured today while breaking in a new upper ... single round in the mag, pressed the release and ... BANG! A little later on, with three rounds in the mag, pressed the trigger ... round fired. Everything is ok. Pressed the trigger again ... double BANG!

I went back to single loading to finish out the box. Total rounds fired ... 40. Two slam-fires (including the double). Two failures to extract. One failure to feed.


First slam-fire was on the second round fired (while I was still single loading the magazines). The double was on rounds 27, 28 (of 40).

At this point the ammunition is my prime suspect, Winchester "White Box" .223 Rem, 62 grain but I would have to say that ARs do, in fact, slam-fire.



I did inspect for a frozen pin after the first slam fire. I didn't expect one (frozen pin) since I had personally cleaned and inspected the gun last night and it was the second round of the day. I also didn't expect it to foul up too much since it is a piston operated upper (ZM Weapons).


The upper was brand new and unfired (except for factory). The lower is a relatively new (about 200 rounds) RRA. Both (upper and lower) were cleaned, inspected and lubricated properly before the trip to the range. The lower has functioned flawlessly for those 200 rounds when mated to a White Oak Armament upper (all Black Hills .223 Rem 77 grain).

I know BR said that the bolt face could cause the slam fire but the two casings did have firing pin strikes with no other dimples or scratches on the primer face.

I am begining to suspect the recoil spring on the ZM upper. It does seem rather robust. This upper might require the harder primers found in 5.56 NATO. Unfortunately I don't know it all yet so I'm still researching.


Tavor 21 Slamfire video on youtube.

Notice how many rounds the guy fires. If he had a mechanical problem he would have recurring slamfires, but he did not. When you see the slamfire, notice that the finger is not on the trigger. He was running Federal American Eagle (federal primers) and Winchester ammo. Winchester redesigned their primers in 1999 to make them more sensitive.

This weapon slamfired in battery. The risk with Garands and M1a’s, is that they have often slamfired out of battery.






Watched an AR Slam-Fire Saturday

Posted 20 http://www.usrifleteams.com/forums/index.php?showtopic=13132&view=&hl=slamfire&fromsearch=1 April 2009 - 09:10 AM



I was scoring my firing-point partner Saturday during offhand and he had a slam-fire on about the 5th round. We're talking about an experienced shooter here. Multi-year state HP champion, generally shoots 199-clean offhand, not to mention he's a hell of a nice guy. The bullet hit the dirt about 10 yards in front of the firing line. I was watching him closely trying to learn something from his technique, but didn't expect to learn this. I know his finger was off the trigger for certain but his muzzle was decidedly pointed earthward when he closed the bolt. The area downrange is uninhabited for many miles, so at this range folks are a bit lax about closing the bolt while rifle is pointed toward the impact area. After that, he was pretty careful about keeping it level. He was shooting an AR spacegun. He thought it might have been due to the bolt carrier weight he had just put in for testing before this match. My suspicion is high primer, but he could be right. Another possibility is his loading technique. He places the round through the ejection port, then tips the muzzle down and jiggles the round fully into the chamber prior to closing the bolt. I have always thought it best to leave the cartridge on top of the magazine and let the bolt "strip" and chamber it from it's "natural" position. In any event, let this be a lesson to all of us. Closing the bolt is an inherently risky event. Point yer rifle at the backstop when you push that button. My buddy lost the match as a result of his slam-fire, but next time it could be a lot worse.



Posted 30 May 2009 - 08:09 AM

I am the person Heman referred to having a slam fire on a bolt rifle. The rifle in question is a Stolle BB Panda action with a Kelbly trigger set at 14 oz. The system is two years old and has several thousand live rounds through it as well as countless dry fires. After the match, I re-weighed the trigger and it still breaks at 14 oz. The only thing that was found was a very small piece of dirt on the sear engagement notch, but I doubt that this was the cause of the slam fire. I tried to re-create the condition 8-10 time on the line, without success, then again at home. I KNOW I didn't have my finger on the trigger when I closed the bolt, so that scenario isn't a suspect either. I just returned from a two day Palma style match where I fired over 100 rounds and not a single hick-up with the system. I guess it will just get chalked up to one of life’s great mysteries.
Be safe,
Lloyd



http://www.arizonashooting.com/v3/v...sid=588d04cdaf6def94be9f899784f80c31&start=15



12 April 2011



I have had ARs fire unintentionally before when the bolt hold-open is released and the bolt slams home. Usually this has happened with reloads, due to use of soft commercial primers and the free-floating firing pin design of the weapon. The milspec primers are slightly harder to prevent just such events. Many claim that the low wieght of the alloy pin makes this unlikely,...but I've experienced it and know better. Nearly took my big toe off once when I releoaded a fresh mag and let the bolt fly home (finger off the trigger, of course).


If the weapon had seen a lot of rounds fired since the last cleaning, the carbon fouling build up that the direct gas system is notorious for could have slowed the rotating and closing of the bolt just enough, that when the sudden slowing of the bolt assembly's forward movent allowed the free-floating firing pin to hit forward on the soft commercial primer,...detonation occurred before complete locking of the breach.


Posted 20 April 2009 - 10:43 AM

Gary,

I disagree.

It's happened to me.

I've found that dropping the round entirely into the chamber and letting the bolt close with full momentum isn't the best idea.

I now leave the round resting on the magazine and let the bolt "pick it up" as it closes.

Free-floating firing pins and occasionally sensitive primers can lead to this.

Pamf,
Gary brings up a good point about the trigger issue. Another consideration is the primer. I have seen 2 slamfires in an AR15. Both occured during an offhand string, 2 shots in a row. The shooter is a very experienced reloader and highpower shooter. It never happened again to him. He was using WSR primers. Perhaps it was the primer's "sensitivity," a couple of high primers, or a combo of the two.
The occurance sure did shake his nerves though. Both rounds impacted 10-20 yds in front of the firing line.
JW


Posted 20 April 2009 - 12:02 PM

I had it a few years ago practicing off hand with winchester white box in my service rifle.

Second shot of the night, shot went into the ground in front of me. I put the rifle down and tracked down my 2 ejected brass. Looking at the primer strikes, one had metal flow out into the firing pin hole in the front of the bolt. So, instead of a primer srike like an innie belly button, one of the brass had an outie. No damage to the rifle.

Whats most amazing about your post PamF is the 199 to 200 part!

Ryan





Posted 20 April 2009 - 12:46 PM

I've had two slam fires and both of them scared the beejiminees outta me. One of the more experienced shooters in my club made the observation that slams seem to happen more often when the muzzle is depresseed as the bolt goes forward. He postulated that the firing pin is already lying forward from gravity almost as if it was preloaded. He figured that as the bolt rode forward with the pin already out, if the primer was gonna go that just gave it the extra opportunity to do so. Since that time I've never let the bolt go forward with the muzzle depressed. I have no idea whether his idea has any merit but it makes me feel safer. For what that's worth. LOL



Posted 22 April 2009 - 11:06 AM

We had at least 2 MIA's over the years at New Holland that had rounds go off when the bolt was closed.
The reason I am able to think of at least 2 is the severe damage to the rifles. In the 2 listed instances the rifles were damaged to the point the receivers were cracked and or broken.
We have an AR-15 do the same thing a time or 2 a year. We have not had rifle damage from the AR-15 slam fires.
My finding at the end of the M1A era and start of the AR-15 era was to completely ensure an AR-15 will not slam fire is to install a light weight firing pin.
Sincerely,
Paul



Posted 22 April 2009 - 12:31 PM

I had a slam fire several months ago. I was just at my regular local club's range doing slow fire standing practice. Put the round in the ejection port, sort of tipped my rifle forward very quickly to let inertia start the round in the chamber and dropped the bolt. Round went off about 10 feet in front of me. I make an effort to keep the rifle parallel to the ground when dropping the bolt, but get lax about it sometimes.

I was using handloads. Hornady 75gr HPBT, 24.0gr RL15, Remington 7-1/2, LC03 brass. I'm betting the primer was a bit high, because it was once fired brass from military source and I used a Dillon Super Swage tool to just barely swage the pockets (keeping them tight as possible, but still accept a primer).



Posted 23 April 2009 - 01:58 PM

I g=had a slam fire with a Garand in the first highpower match I EVER shot. Really unnerved my. I was a reloading greenhorn, but others found some issue with the dies a friend had loaned me. learned a lot that day. I've always remembered that.



Posted 03 May 2009 - 08:52 AM

We've had only one instance in the 11 years I've ran local matches. AR15, handload. The same gun has been used many times since w/o any problems. The round impacted the ground 15 feet in front of the line - not a big problem with me compared to having the muzzle raised and the bullet leaving the range.
Me, guess like most, load with the muzzle slightly depressed, drop it in, and hit the bolt release. Bent several rounds trying to drop 'em on the follower. Haven't lost 10 points to slamfire yet, although I have employ many other methods of losing points !

Posted 29 May 2009 - 11:46 AM

I saw two slam fires by the same shooter in the same offhand string.
He was a good shooter who posted a poor score for the day because of this.
I never found out what caused this in his rifle that day but it reinforced the absolute importance of having the muzzle ALWAYS pointed in a safe direction when closing the bolt on live ammunition. (in any firearm)
Both rounds impacted the ground a few yards ahead of him but later, in the same match, I witnessed him closing his bolt with the muzzle well above the horizon. ????????
Bullets impacting the ground will tumble and have a limited flight distance but ones angled above the horizon can pose a much more serious hazard.
Trying to close the bolt with the rifle aimed at the backstop is, in my opinion, asking for trouble. I always keep my muzzle down when closing the bolt and have never experienced a slam fire in my own firearms.
Most folks close their bolts sky high during their rapids and I wish that they wouldn't

Posted 29 May 2009 - 12:33 PM

I had mine to slamfire monday while chronographing some loads. It was completely horozontile on a front rest when I loaded and closed the bolt. I'm just glad it was pointed downrange and wasn't pointed at the chronograph when I closed the bolt. Scared the crap out of me though.

Slamfire, how is it scored?

http://www.usrifleteams.com/forums/index.php?showtopic=13846&view=&hl=slamfire&fromsearch=1

Posted 21 July 2009 - 12:05 PM

How do you score or count a slamfire? Is it considered as a miss or are you allowed to fire over with another round and disreguard the slamfire? I am referring to having a slamfire while shooting slow fire 200 or 600. The reason I'm asking I have had 2 slamfires one was recorded as a miss at one range and the other one was disreguarded and I was allowed to fire another round in it's place at a different range. Just wanting to know the proper procedure. Tim


Posted 21 July 2009 - 04:05 PM

I never had this happen until I bought some CCI400 primers. The rem. 7.5 never slamfired on me. I'll be glad when the CCI's are gone.

Posted 25 July 2009 - 06:12 PM

I had it happen to me twice in the same stage of a match, standing slow fire, with the newer Winchester SR primers. I was able to borrow a friends extra amo and finish the match. I now only use Rem 71/2's at matches and have never had a problem since. The old Win SR's were harder. I have used CCI mil spec primers on my practice loads with no issues also



http://www.thehighroad.org/showthread.php?t=650722

#1

IMtheNRA

Member



Join Date: December 24, 2002

Posts: 700

AR slamfire using CCI SR primer - pic included


Well, after loading thousands of rounds of .223 using CCI SR primers, I finally had a slamfire. I pulled the trigger once and two rounds fired. Here is a pic of two cases - the tiny firing pin mark is the round that slamfired, the other is a normal mark for comparison.

I picked up a ton of harder CCI Bench Rest primers to use in my AR from now on.


AR15 slam fire

http://www.thehighroad.org/showthread.php?t=734959

post 1

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.

Post 41

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



Post 36

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


Out of battery slamfire in a AR15


http://forums.1911forum.com/showthread.php?s=c0fe71be991c9f0f77a26713ff817b94&t=423194&page=2


Got my first slamfires today in my new AR?


July 24, 2008, 05:36 PM

BsChoy

Join Date: June 14, 2005

Location: Upstate NY

Posts: 1,344


I had 5 slamfires all with LC brass I reamed and FL resized. I just ordered a primer pocket uniformer, should this fix my problems or would I need to go about it a different way?



I use federal primers and have never had an issue in my M1 before. The primers were seated by a lee hand primer and all were at least flush if not further. They did seat with some mild resistance but nothing I would think would crush a primer cup. I actually had no issue shooting the commercial brass (winchester) reloads with the same primers in it just prior to shooting the military brass reloads [/b]


Proving a rifle fired out of battery?

https://www.thehighroad.org/index.php?threads/proving-a-rifle-fired-out-of-battery.823198/


Yes, it is possible for some semi-auto rifles to fire out of battery. I was doing a consulting job for Lake City Army Ammunition Plant a few years ago on M855 ammo. During the course of that, the Army rejected a very large lot of ammo because of a case head failure. Since I was the so-called outside expert, they asked me to look into it while I was there.

I was shown a picture of the failed cartridge, and had not seen anything like it. I had to sleep on it overnight before I realized what had happened.

The last quarter inch of the case had failed catastrophically. What I realized the next morning was that the rear part of the case was expanded to larger diameter than the chamber. That is impossible if the cartridge is fully chambered.

The failed cartridge was fired from an M16, which, of course, has a floating firing pin. Probably a small piece of grit had lodged in the mechanism, momentarily locking the pin forward.

So I wrote a quick report pointing out that it was obviously a firearm malfunction, not a cartridge malfunction. LCAAP was then able to move several trucks loaded with that lot of ammo.

Later, I called Rocky Raab who is a former gun writer, and who served in Viet Nam. I started to describe the event, and he didn't even let me finish. He was laughing pretty hard, and immediately knew what had happened.

It was not that long ago that slamfire deniers were a dominant group on web forums. CCI was the only vendor offering their mil spec line to the public so if you are a CCI hater, than denying slamfires is natural. These slamfire deniers also used a decades old Army coverup of the characteristics of the Garand/M14, which were the most slam firing mechanisms in the American market place, to bolster their case.

The great thing is, the web and honest people have drowned out slamfire deniers. There was an active slamfire denial campaign in the pages of the American Rifleman, going back to the early 1960's. The retired Army Ordnance retirees who wrote for the American Rifleman wrote that the only causes of slamfires were "high primers and your worn out receiver bridge". The only semi auto rifles that civilians had, in high quantity, and were shooting frequently, were M1 Garands and State Association M14's. When these rifles slamfired inbattery and out of battery, the Army, with its supporters in the NRA, persistently denied there was anything wrong with the Garand design. You can find their articles in which they claimed that the Garand mechanism positively blocked the firing pin and prevented incidental contact. You can find on many web sites those Parroting the Army coverup claiming the receiver bridge is a positive firing pin block. Which is not true. And they also ignore primer sensitivity. Just as the Army Ordnance writers did writing for the American Rifleman. And knowing pieces of what those guys knew, it is telling that they provided absolutely no discussion about primer sensitivity. A primer is a primer is a primer. The Prime Davidian, was the Army expert during Ichord hearing, and he was the lead in developing less sensitive primers for the M16 mechanism. The Army had a slamfire problem with early M16's, the Prime Davidian helped reduce the slamfire incident rate, through less sensitive primers and the Army created a lighter firing pin. He also sent letters to industry, under his letterblock, explaining the characteristics of the M16 primer issues. And yet, the Prime Davidian, in an Dope Bag reply in the American Rifleman, absolutely, positively ignores primer sensitivity and states that the only causes of slamfires are high primers and your worn out receiver bridge. At the time he wrote that, information had not been de classified so we did not know about that period, and we did not know his involvement. I can only conjecture why the Prime Davidian and all his American Rifleman cohorts denied the primary cause of slamfires, knowing that the Army created its own less sensitive primers to use in the M16 and M1/M14 rifles to reduce the slamfire rate in these weapons. These "mil spec" primers were not available to civilians till 1999 when CCI released them to the civilian market.

However, once the web allowed shooters to share their experiences without having to go through some editor of an in print magazine, and with the arrival of literally millions of AR15's starting in the 1990's, the dogma that slamfires were only due to your high primer and worn out receiver bridge began to reveal its contradictions. The AR15 does not have a receiver bridge, and many reports of slamfires with factory ammunition made the claim that slamfires were caused by high primers rather dubious. I think the shooting community has become aware that primer sensitivity has something to do with slamfires.

 

[243winxb]

https://www.thehighroad.org/index.php?threads/ar15-slam-fire.734959/

A slamfire is a rare event, but happens. The hammer is still cocked.

When the hammer is riding/following the carrier/bolt down, will the round be fired? May depend on the type of bolt carrier?

Sp1 possible. M16 no. My guess.

But if a light trigger pull allows the sear to delay the hammer fall, a slight delay, the round will fire.
Gun fires, bolt moves back to cock hammer. Hammer makes contact with sear, bolt moving forward, the hammer slips off sear. Hammer delayed, rifle fires.

The M16A1 auto sear provides this delay when the trigger is held back on full auto.

 

[Varminterror]

In a non-shrouded-FP carrier, as long as the hammer tip is notched, the hammer won’t, or at least should not, by design, be able to fully follow. The notch in the hammer catches the FP and stalls the BCG. Out of battery.

For shrouded-FP carrier, if the hammer follows, it also typically does not fire. Honestly, it’s almost disappointing that it does not. But you can witness it for yourself. Assemble the FCG without the disconnector in place - which would cause the hammer to follow the carrier if the trigger is held to the rear during the shot. I believe many, many AR owners have been disappointed to realize this does not result in a full-rattle-trap rifle, but rather shifts the other way, producing a single shot, and worse, one which requires a loaded round be wasted via ejection between each live shot.

 

[entropy]

Just another reason I use CCI 400's; never had it happen with them, though to be fair, it's never happened with factory Win. (the few boxes I've shot) either.

 

[ArchAngelCD]

Over the past few years if I can find the CCI #41 primers I use them and Remington 7 1/2 primers too.

Over the years I have used many many CCI400 or CCI450 primers in my AR ammo without a problem and would again. I also used Winchester SRP but not since they changed them because of the reports they are softer.

During the shortage I used various off shore primers which were reported to be for 5.56 semi-auto use, again without problems.

Today I tend to stick with CCI because they have never failed me.

 

[Metal God]

The little extra speed that gravity gave to the bolt caused enough slamfires through the shooting stool that the NRA forbid loading your rifle on the stool.

I'm not buying it , especially if you're talking CMP , Service rifle matches . Those rifles likely have similar triggers as mine does . Mine can be set to 1lb or less on the second stage and even so light that every time the BCG flies home the hammer drops with out touching the trigger . Maybe those guys should be bringing a safe rifle to the match rather then trying to get every last oz out of there triggers . It was likely easier to not allow the shooter to load that way then to check every rifle every match for safety . Until a test is done that uses a hammerless FCG and you get slamfires with the modern AR-15 style rifle I'll be a little skeptical .

On a side note , Nice to see you again Slamfire . I've missed your post on the other forums I frequent but you appear to no longer post at . It is our loss you are no longer there .

 

[Metal God]

For shrouded-FP carrier, if the hammer follows, it also typically does not fire. Honestly, it’s almost disappointing that it does not. But you can witness it for yourself. Assemble the FCG without the disconnector in place - which would cause the hammer to follow the carrier if the trigger is held to the rear during the shot. I believe many, many AR owners have been disappointed to realize this does not result in a full-rattle-trap rifle, but rather shifts the other way, producing a single shot, and worse, one which requires a loaded round be wasted via ejection between each live shot.

Any theory a to why ? I've never had the guts to try it . Interesting though because mine was absolutely doubling and tripling with the disconnect out of spec according to the manufacture . Maybe it hung up just enough or let go to early .

 

[Varminterror]

A slipping disconnector is not the same as no disconnector. The hammer needs some free space to swing and build momentum before it contacts the FP, else it’s just a hard follow with a deep FP kiss on the primer.

Guys can run bolts on stickshifts hard and fast enough to slip a trigger and effectively slamfire, so I’m not saying a slamfire CAN’T happen in an AR, but in my experience, as I said in my first, guys make a huge deal about primer choice and pin mass in AR’s because they’re worried about the little dimple their pins leave on primers just by closing into battery.... it’s a lot of smoke and almost never any fire. It makes some people’s brain itch to see that dimple and they end up in a panic. I expect it happens about as often as people start fires with cell phones at gas pumps, or maybe how often Narwals get hit by lightning.

 

[Walkalong]

A slipping disconnector is not the same as no disconnector. The hammer needs some free space to swing and build momentum before it contacts the FP, else it’s just a hard follow with a deep FP kiss on the primer.

Yep, has to be some delay. How much is a good question, and may vary by firearm.

 

[Ej3]

I was following the thread regarding "Problem with Misfires" and Walkalong posted to check primer depth using the end of your digital caliber. I never realized this capability and just did some checking on my hand loads compared to some factory ammo.

I checked about 6 different .223/5.56 rounds from different manufacturers. All are between 0.007" - 0.008".

My reloads are between .0035" - .004". So I suspect that this was the issue with the two slam fires I experienced.

But before I realized that I could check the depth of my primers, I had already seated some completed rounds a bit deeper using my Frankford Arsenal Platinum Series Perfect Seat Hand Primer. These completed rounds are now about .009" - 0.010". I just tested 10 rounds and all fired fine at these depths.

So from this point forward, when using the WSR primers for my .223 hand loads I will seat them to 0.008".

To some extent it is embarrassing to admit that I did not realize how to check the seating depth of my primers using the digital caliber. But being honest about it and posting a follow-up comment will hopefully help someone researching this problem of "slam fires" with their hand loads. It may be nothing more than not seating the primers deep enough.