I've been having bump fire issues with my AR lower and Fed SR Match primers. I'm on my second box of Fed primers and this started to happen a month ago with both the 5.56 and 300BLK uppers. I have been getting into hotter loads lately but can't determine a direct correlation. The going theory is that the Fed primers are soft and more susceptible to bump fires. I was planning to switch to CCI 41 primers and then saw that Johnny was having a similar problem. Fortunately, I didn't shoot out my camera tripod like he did (not that I use one).

https://youtu.be/7Il1ix-E_cA?t=6m49s

I stopped by Prime Sports and noticed he had Winchester primers but didn't get any. Are they as soft as Feds?

Bump fire or slam fire?


Sent from my iPhone using Tapatalk

I've never had a slam fire.  Slam fire is when the bolt and firing pin go forward and set off a round without pressing the trigger.  Bump fire is when you have a stock or hold the rifle a certain way to replicate full-auto with a semi-auto.

Everything stock and unmodified?

Had Fed primers pierce several times but not a slam fire. Lee Precision states not to use Federal in their priming tools.

Truth is I'm not sure to call it a slam or bump. Regardless, it's where the free floating pin hits the primer when returning the BCG. I installed a 2.5# trigger. If the problem persists with the CCI primers, then I'll switch back to the stock trigger. Is it possible for the trigger to cause primer problems? How?

I can see how the Fed primers could be a problem. Ironically, they were the most accurate and the highest velocity SD of the group.

You need to troubleshoot further. Is it your trigger or your reloads? That Johnny video shows a possible trigger problem. Several things contribute to a slam fire. A high primer. Possibly a very sensitive primer (Federal). Johnny's troubleshooting is all over the place in that video. He blames the primers and talks about all kinds of factors that are likely not relevant to the problem he experienced. Anyways my 1.5 cents

He'll likely troubleshoot it further tomorrow. He makes several videos in a day, then spends the following days releasing each video. Today was part two of 223 primers, not that there's much difference. I'm sitting in the Kauai airport so will check out the video when I get home.

It's likely the trigger or the primer. I'm planning to head to range on Thursday

Truth is I'm not sure to call it a slam or bump. Regardless, it's where the free floating pin hits the primer when returning the BCG. I installed a 2.5# trigger. If the problem persists with the CCI primers, then I'll switch back to the stock trigger. Is it possible for the trigger to cause primer problems? How?

I can see how the Fed primers could be a problem. Ironically, they were the most accurate and the highest velocity SD of the group.

Does it do this when you send the bolt home (if loading on an open bolt) or when you pull the charging handle to chamber the first round?  If it does it then, it's a slam fire.

Or is the gun firing off a second shot after a single pull of the trigger?  If it's doing this, then there are some trouble shooting that can be done to eliminate variables.

To me, bump firing is holding the gun in such a manner where the recoil impulse sends the gun backwards slightly and then forward pressure on the gun pushes the trigger against the trigger finger, which is held somewhat firm, and then fires off another round.  I've seen people do this intentionally often and somewhat to a lesser extent unintentionally. 

I've personally never had a slam fire.  After unloading, I've often noticed a shallow depression in the primers, which was evidence that the firing pin had hit the primer upon chambering the round, but not enough to ignite the primer. 

EDIT: Just watched the video.  Not much though, but just the part where the "holy smokes".  Tough to tell there as there seemed to be a sort of break, like video editing.  However, it appeared that he shot one. Let the trigger reset and he appeared to pull the trigger.  In that case, I don't see it as a slam fire as the bolt would already be home.  I was thinking maybe the hammer went forward on reset, but after watching it a few times, I didn't see that.  I'll go back later tonight and try to watch the trouble shooting part of the video.

Depends how the round is loaded too.  If you're feeding rounds directly into the ejection port with no mag or an empty mag loaded, then there's less resistance when the bolt goes forward.  So the bolt/firing pin will hit the primer harder than if it's stripping rounds out of a magazine.

Or could be something wrong with the trigger where it's firing off 2 rounds with one trigger press, but this would affect all different types of primers.

I have had 2 slam fires using Federal SR Match primers in my AR-15. I stopped using them.

He'll likely troubleshoot it further tomorrow. He makes several videos in a day, then spends the following days releasing each video. Today was part two of 223 primers, not that there's much difference. I'm sitting in the Kauai airport so will check out the video when I get home.

It's likely the trigger or the primer. I'm planning to head to range on Thursday

What's your relationship with Johnny?

Does it do this when you send the bolt home (if loading on an open bolt) or when you pull the charging handle to chamber the first round?  If it does it then, it's a slam fire.
Or is the gun firing off a second shot after a single pull of the trigger?  If it's doing this, then there are some trouble shooting that can be done to eliminate variables.

About every fifth round, a second round usually goes off after I squeeze the trigger, hold, and release the trigger. Sometimes, the rounds go bang-bang but not often. I then have to pull the charging handle a bit to recock the bolt.

I have had 2 slam fires using Federal SR Match primers in my AR-15. I stopped using them.

I agree. That's the consensus. The alternative theory is that the trigger is causing it.

What's your relationship with Johnny?

Um... I thought it was interesting that he started to have the same problem I was having. Why?

Step by step plan for you to trouble shoot:
- get 100 rounds of factory ammo
- shoot them
- if you get slam fires its your trigger
If everything checks out OK with the factory ammo it is likely your reloaded ammo
- shoot your suspected reloaded ammo - if you get slam fires its your ammo. either the make of your primers are culprit or they could be sticking out of the case (unlikely as the ammo would likely not chamber in an AR)

Thanks for reminding me. I'll try the PMC Bronze ammo I have.

Best post so far, love this song...

I have a JP fully adjustable trigger in my AR and I apparently had it adjusted incorrectly the first time I took it out. I won't go into all the details but all it took was about 30-40 rounds of crud to get into it and started doing something similar. But once it started it was repeatable. So I suggest you explore the primer issue first and then go for the trigger if the commercial ammo does it as well.

One question. Do you think it fires the second round when you release the trigger? In other words, if you hold the trigger back hard after the shot goes off for a few seconds and then when you release the trigger it fires again?

I have a JP fully adjustable trigger in my AR and I apparently had it adjusted incorrectly the first time I took it out. I won't go into all the details but all it took was about 30-40 rounds of crud to get into it and started doing something similar. But once it started it was repeatable. So I suggest you explore the primer issue first and then go for the trigger if the commercial ammo does it as well.

One question. Do you think it fires the second round when you release the trigger? In other words, if you hold the trigger back hard after the shot goes off for a few seconds and then when you release the trigger it fires again?

When I watched the video, that's what I suspected.  That a second shot was going off on the reset.  But then watching the slow mo, it was a double that was so fast that I didn't pick up the second.  Hard to tell from the video, but he seemed to be shooting in the click-bang-pause-reset/click method. 

I've seen a ton of Glock triggers start doubling when folks start "polishing" certain parts of the trigger assembly.  Never really seen it on an AR, but don't doubt that it can happen.  I've seen the fire on reset though, but not too often. 

About every fifth round, a second round usually goes off after I squeeze the trigger, hold, and release the trigger. Sometimes, the rounds go bang-bang but not often. I then have to pull the charging handle a bit to recock the bolt.

SNIP

You're getting good advice here. 

However, I just wanted to clarify, since you're sort of all over the place.

So it sounds like there are a number of different variations.  See if I got this right.

Variation #1 - Click of breaking of trigger - bang - still holding trigger to rear - release trigger - bang (does the second bang occur on the reset?)

Variation #2 - Click of breaking of trigger - bang & bang - still holding trigger to rear - release trigger - dead trigger (bolt is forward, but hammer is not cocked?)

When I watched the video, that's what I suspected.  That a second shot was going off on the reset.  But then watching the slow mo, it was a double that was so fast that I didn't pick up the second.  Hard to tell from the video, but he seemed to be shooting in the click-bang-pause-reset/click method. 

I've seen a ton of Glock triggers start doubling when folks start "polishing" certain parts of the trigger assembly.  Never really seen it on an AR, but don't doubt that it can happen.  I've seen the fire on reset though, but not too often.

I was not going to get into too much detail, but since we are discussing it....

I really like the JP trigger but it can be adjusted down to the 'nth degree. Which I did a little too much. So after about 30-40 rounds it went full auto!!!    Surprised the you know what out of me!!! The RSO's didn't hear it the first time. I took it home and cleaned it and next visit it did the same thing. But this time one of the RSO's was standing within earshot and came over to give me crap about it. I called JP and they admitted it can happen and explained what I had to do to fix it. It was easy enough to adjust but just took a little time and patience.

The scenario I asked RK about in my previous post is something I saw on someone else's AR at the range a couple of years ago. I don't remember what trigger he installed or if he had worked on the trigger himself? Geez my memory is shit lately. Anyway, he was getting double shots almost every time he pulled the trigger. When separating the upper and lower it would not repeat. Once the upper was back on and a magazine inserted with some ammo it would fire one round when pulled and another when released most of the time. Took me a while to figure it out for him. I originally thought I was double tapping the trigger unknowingly.

I am a fairly new AR owner. Since 2012. I jumped into reloading for it without a whole lot of research. I loaded a couple thousand rounds of .223 using Federal primers before I heard about them being soft enough to allow a slam fire. I have probably put 600-800 rounds through it without a slam fire. I know this proves nothing, but I have since purchased harder primers for reloading for my AR just in case. I still have about 1,500 to shoot up with the Federal primers. I can use up the remaining Federals with my bolt gun. Personally, I will never use Federal primers again as they are slightly larger in diameter than say CCI's and take a lot more effort on my hand primer to press them in place. And with arthritis setting in it means more pain and less reloading per day for me.