Had a slam fire at the range

**Will3212** · June 9th, 2023, 10:37 AM

I was shooting my DD M4 AR15 at the range and had my first slam fire. The bolt was open, I loaded 6 rounds of new PPU 5.56 into the 30rd magpul mag., then hit the bolt release, the bolt went forward and immediately 3-4 rounds went off.

I tried to duplicate this right after but couldnt, this did occur another 2 times out of 20 or so mag. change - release bolt.

I have run over 1000 rounds in this DD AR15 before this and never had a slam fire. I disassembled it when I got home and cleaned the BCG/rifle, everything looked fine.

I'm thinking it was out of spec PPU ammo, or possibly a stuck firing pin.

What's your thoughts on this? It was a scary experience.

**streaker69** · June 9th, 2023, 10:43 AM

Delete your post and consult an attorney.

**JoshIronshaft** · June 9th, 2023, 10:45 AM

A good reminder that you should always chamber rounds with the gun pointed in a safe direction.

My first suspect would be a firing pin stuck forward, caused by debris or gunk.

It could be super sensitive primers, but I would be surprised. The AR has a floating firing pin and it does kiss the primer when a round is chambered, but I don't think I've ever heard of primers this sensitive being loaded in new factory ammo. Even by mistake.

What did the primers looks like? Normal? Or were they showing unusual deformation or puncture?

Another suspect could be something in the fire control group.

Did you happen to notice if the hammer was forward after the slam fire? This would be indicated by a dead trigger. If that is the case, then something is releasing the hammer when the bolt goes forward.

Did the trigger feel weird when shooting?

I would remove the trigger and hammer and look for excessive wear, displaced material, or a foreign object. I have received a hammer in a LPK that was not properly heat treated and within a low number of rounds the hammer was damaged where it engaged with the trigger.

**PASE717** · June 9th, 2023, 10:56 AM

If you've already ran 1K rounds tru it without issue, then I would say the ammo is highly suspect. You may want an armorer to take a look at it just to confirm.

**JaySmith** · June 9th, 2023, 10:58 AM

Haven't had that, but around my parts there would be a fudd calling the atf on me for having a fully semi automatic mass murder weapon that fires more than one round per second.

I have a DD AR15 and i have never experienced that issue. I would think if it was firing pin you would have an out of battery discharge. When the 3-4 rounds went off why did it stop? Did it jam? did it load a cartridge that didn't go off?

**Will3212** · June 9th, 2023, 11:05 AM

Originally Posted by JoshIronshaft

A good reminder that you should always chamber rounds with the gun pointed in a safe direction.

My first suspect would be a firing pin stuck forward, caused by debris or gunk.

It could be super sensitive primers, but I would be surprised. The AR has a floating firing pin and it does kiss the primer when a round is chambered, but I don't think I've ever heard of primers this sensitive being loaded in new factory ammo. Even by mistake.

What did the primers looks like? Normal? Or were they showing unusual deformation or puncture?

Another suspect could be something in the fire control group.

Did you happen to notice if the hammer was forward after the slam fire? This would be indicated by a dead trigger. If that is the case, then something is releasing the hammer when the bolt goes forward.

Did the trigger feel weird when shooting?

I would remove the trigger and hammer and look for excessive wear, displaced material, or a foreign object. I have received a hammer in a LPK that was not properly heat treated and within a low number of rounds the hammer was damaged where it engaged with the trigger.

I didnt look at the primers of the casing, I was too shocked by what happened when it occured.

When I got home, I loaded an empty mag., released bolt, then separated the upper from lower to see if the hammer was cocked/down or up.
I did this 5 times and the hammer was down everytime which is normal, hammer never releases to strike firing pin without trigger pull.
I inspected the hammer, firing control group, everything looks normal...unless its something hidden.
I used Ballistol to clean and lubricate parts.
Any other test I can perform to pin point the problem?

**Will3212** · June 9th, 2023, 11:08 AM

Originally Posted by JaySmith

Haven't had that, but around my parts there would be a fudd calling the atf on me for having a fully semi automatic mass murder weapon that fires more than one round per second.

I have a DD AR15 and i have never experienced that issue. I would think if it was firing pin you would have an out of battery discharge. When the 3-4 rounds went off why did it stop? Did it jam? did it load a cartridge that didn't go off?

I don't know why it stopped. It didnt jam, I think it loaded a cartridge that didnt go off.

**Delkal** · June 9th, 2023, 11:11 AM

Clean the firing pin channel with a pipe cleaner. See if any crud comes out. Check for burrs.

**Will3212** · June 9th, 2023, 11:57 AM

I reached out to DD, and the tech told me it could be the trigger housing pins are walking. Would this cause a slam fire?

**GunLawyer001** · June 9th, 2023, 12:00 PM

Could be ammo with soft primers, dirt in the firing pin hole, maybe the recoil spring is too strong and you're short-stroking so it doesn't engage. Maybe a combination of things. Make sure the pins are all engaged in the FCG.