Ruger Forum banner
1 - 20 of 27 Posts

·
Registered
Joined
·
329 Posts
Discussion Starter · #1 ·
Greets All, Long Post :coffee:o_O

AR-15 Slam Fire, Myth or Fact?

Who here has first hand experience with AR-15, reloaded ammo, and slam fires?
I personally do not have first hand experience. My reloads used an "approved" AR-15 style primer.

In general, there's enough crap on the internet to confuse a lawyer. More specifically, there's enough crap on the AR forums about slam fires to confuse a CDC spokesperson.

I would like to discuss the myth or fact, and determine reality. (I've done some personal research, and have my own conclusion, but I can certainly use more info/experience).

1. If slam fires are real, "how" do ammo manufactures "prevent" slam-fire with .223 ammo?
There are way too many cases of folks firing .223 ammo without a slam fire, then those reporting it.

2. Where I'm at today. The only primer available is the Non-AR style primers, can they be safely used?
I'm zero balance on CCI 41 primers, and only have Federal standard small rifle primers.

3. Lastly. I've read, seating the primer at .003 below flush is "a way" to deter slam-fire. (If it even exists).

For the record: I have measured handfuls of Lake City NATO and found every primer seated at .0025 - .0032 below flush of different lots/batches/year groups. That's rather positive consistency, and has driven my personal thoughts on this...

For clarity: AR-15 has a free floating firing pin design. The firing pin is known to "tap" the primer during the chambering cycle. This function has been "coined" slam fire conditions, when the "tap" generates enough force to detonate the primer, prior to trigger pull. This "can be" a dangerous situation (run away gun) "if" it happens, plus the weapon is firing prior to fully chambering, which causes other issues, if not halted immediately (or so we have been fed to believe). EDIT: The use of AR style primers (thicker cup) eliminates this phenomenon.
 

·
Registered
Joined
·
2,272 Posts
My understanding is the firing pin was lightened (weight reduced) on the modern guns and any ammunition/primer type should be safe. I am far from the AR guru here so am following this for my safety also.
 

·
Super Moderator
Joined
·
5,328 Posts
Slam fires are possible, but I have never seen one personally on an ar. If I pull an unforced round out of the chamber, you can see the little dimple where the firing pin kissed the primer, but have never had one go off. I do know it’s always a possibility, yet I don’t use the harder military or AR primers. I use just good old normal primers. That said, I have seen M1A rifles slap fire, a couple times. It’s happened a couple times in service rifle matches where an M1A shooter on the line has one slam fire.
 

·
Premium Member
Joined
·
818 Posts
Slam fire in an AR is more likely a trigger group gone binary or full auto. I have had one go binary and it is surprising. I replaced the whole trigger group. I imagine it could happen if the firing pin froze in the forward position but that would take some extraordinary conditions. SKS have a record of the firing pin freezing including 1 death that I know of. It should have nothing to do with the cartridges or primers although the steel case ammo has very hard primers. Maybe because of the SKS.
 

·
Registered
Joined
·
363 Posts
Slam fires are very very rare. I’ve loaded thousands upon thousands of rounds of .223 using standard CCI 400 primers in multiple different AR rifles and pistols without any problems…..none! All of my reloading friends, including competitive shooters, have the same results with standard small rifle primers.
 

·
"The Real Deal"
Joined
·
9,109 Posts
It is possible, the fix is to use the right primers.

I have always used cci priners in my rifles reloads, and knock on wood no issues. You can see that on the AR and garand action it does make a light strike on the primer when charging the bolt. The 9mm AR has a spring to prevent that.

With the idea that they make lighter firing pins for the AR that is likely and reasonable. But also remember with the TONS of ar parts out a heavier pin could be installed unknowingly and result in a possible slam fire if that contributes to the problem.

Always use safe firearm fundamentals, keep it pointed down range, anytime your loading it, wear eye and hearing protection.

So yes its possible, just not normal nowdays but plan for it in the event 1 in 100,000 does slam fire. Its not something i worry about, but plan for just incase.
 
  • Like
Reactions: Corndog and Mark204

·
Premium Member
Joined
·
818 Posts
Mine went binary with a stock DPMS trigger group. I think it was out of spec or improperly heat treated. I replaced it with a drop in.
 

·
"The Real Deal"
Joined
·
9,109 Posts
Mine went binary with a stock DPMS trigger group. I think it was out of spec or improperly heat treated. I replaced it with a drop in.
Seen an anderson trigger do that, its machined differently than most, with serrations on the back of the hammer. I don't use those in my builds.
 

·
Registered
Joined
·
329 Posts
Discussion Starter · #10 ·
20 year veteran US Army .... AR 15s DO NOT SLAM FIRE they can auto fire when trigger group is out of spec. This is nearly 100% caused by WANNABE gun smiths...
I was large caliber, so these plastic pea-pew twenty-twos are new to me. And as mentioned, the AR forums are littered with hipsters and kids who have probably never experienced anything they're talking about, but make for good opportunities to ponder.
I've never seen an early M9 lose it's slide, either...
 

·
Registered
Joined
·
329 Posts
Discussion Starter · #11 ·
Slam fires are very very rare. I’ve loaded thousands upon thousands of rounds of .223 using standard CCI 400 primers in multiple different AR rifles and pistols without any problems…..none! All of my reloading friends, including competitive shooters, have the same results with standard small rifle primers.
Do you seat primer flush or below?
I have a micro adjustable hand primer, and can seat anywhere from flush to max, with .001 increments.
 

·
Registered
Joined
·
8,944 Posts
Slam fires are like UFO’s, everyone’s heard about them but very few have seen one. The ones that have seen one can’t explain what they saw. If this was a “thing” this problem would’ve been corrected what, 60 plus years ago?

It can usually be back tracked to an AR in need of repair/cleaning or improper reloading practices. It’s not complicated.
 

·
Registered
Joined
·
2,272 Posts
I am only a novice AR user. The force/velocity of the BCG coming into battery, from the push of the release, always makes me pay attention. I never chamber an AR round, of any flavor, before ensuring the muzzle is pointed at the ground and my hearing protection is on my head. So far, knock on wood, no surprises.

I do the same with my Mini 30. Actually, with every semi-auto, long or short, I own.

Worms beware.
 

·
Registered
Hirschjäger
Joined
·
909 Posts
I think I had my AR556 double-fire one of my handloads one time. It happened so fast that to this day, I'm still not sure.

I can't discount the possibility that I had a slightly high primer.

Primers are Winchester SRPs.

Aqualung
 
  • Like
Reactions: Mark204 and Tacky

·
Registered
Joined
·
683 Posts
I was at a match where there was a slam fire. Guy was at the firing line and told to load, muzzle down range and when he closed the bolt the rifle discharged (he was disqualified). I don't know what happened; could be crud in the bolt that held the pin forward, non-AR primers, etc. I my experience (XM16E2 fifty years ago) any round that goes into the chamber and isn't fired comes out with a little dimple in the primer. The firing pins don't have springs on them, they just slide around in the bolt, I suppose one could get stuck forward.
.
 

·
Registered
Joined
·
352 Posts
I spent 23 years in Army and Air Force. I never once seen a slam fire. Can't say it won't but I just don't think so.
 

·
Registered
Joined
·
329 Posts
Discussion Starter · #18 ·
For all of us Veterans, M16/M4 usually shall not slam fire, not because of weapon, but the ammo.

My focus is on my next phase of reloaded ammo using non AR-15 style primers.

Thanks to everybody for your feedback. Especially cavediver
 

·
Registered
Joined
·
575 Posts
Maybe GONRA missed it above, but in selfloading firearms
do NOT chamber a round and let the bolt slam home!
Strip a round off magazine (slows down bolt) to avoid
to a POSSIBLE slam fire....
Never good to "play he odds" on gun stuff !
 
1 - 20 of 27 Posts
Top