AR15 slam fire

[heavydluxe]

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]

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]

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]

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]

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.

 

[Slamfire]

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]

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]

See post #35,

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

Joe's

 

[Dolph92]

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]

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]

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]

Oh I found a good image on this topic.





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]

The question is, when the hammer is riding/following the carrier/bolt down, will the round be fired?

 

[Rushthezeppelin]

Oh I found a good image on this topic.





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 ) 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]

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.

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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]

Nice copy and paste from AR15.com www.photobucket.com/M16A1

 

[Dolph92]

@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.