Problem with popped primers

[caelumatra]

A friend of mine and I went shooting this weekend and he had some problems with his BCM complete rifle.

He had 5 primers come out of the casing into his rifle. Once, getting loose into the gas key and jamming the bolt in place with it only coming out after a good deal of force.

I have an extra BCM complete upper and BCM bolt that I have waiting for me to finish a lower for, and I brought it with us (it just stays in my gun case with my complete rifle). We swapped out my extra upper for his in troubleshooting that something was amiss with his upper. However the same thing continued to happen with my other upper. This upper has only had the rounds through it BCM put through it before shipping it to me so it was very peculiar that we were having this problem. We also then swapped out our buffers and springs as he has an H buffer and I have a standard buffer. Still happened.

What he was thinking was it was the ammo. The ammo was the Fiochi 55gr from DSG that I'm sure many of us bought by the thousand when it was on sale earlier this year. And if I hadn't been shooting my rifle with the same ammo with 0 problems at all, I would have agreed with him.

I have a CD lower that I built with I think a DPMS LPK (its been a while since I built it and I bought the LPK from wherever it was in stock so I cant recall if it is for sure a DPMS LPK) with a non H buffer. My upper is a BCM complete that I took the barrel out and changed it out for a BCM barrel (https://www.bravocompanyusa.com/ProductDetails.asp?ProductCode=BCM-BRL-s-MID-16%20STD) with different dimples on the bottom for use with a low pro gas block. My upper also has a battlecomp 1.0 on it and I use a standard BCM bolt.

I have put around 800 rounds of this ammo through my rifle and not one single problem arose. However, within less than 100 rounds of the same ammo through his and he had at least 5 primers pop out of the casings.

The only thing we didnt try and I realized it this morning was putting his factory upper on my CD lower to see if somehow his lower was doing something it shoudnt be doing.

I am truly at a loss on why this would happen and can only speculate that possibly his hammer is striking the firing pin to hard or to deep and it is taking the primers out of the primer pocket.

Any ideas?

[caelumatra]

Oh, also, the reason we swapped buffers out is I had commented to him before but his rifle extracts at about 2 oclock and mine extracts about 430 or 5 oclock. And swapping the buffers did not alleviate this.

Neither of the 2 bolts that had this happen to it have the O ring but do have the black nub within the spring

[ForTehNguyen]

stop shooting that ammo, popped/blown primers are a sign of overpressure. This doesnt sound like a rifle defect.

[arizonaranchman]

It's not the rifle, it's the AMMO...

[caelumatra]

I'm not really disputing here as I would like to solve this problem, but why would it happen to my rifle 0/800 times and his rifle 5/80 times? Shouldn't it, if the problem was the ammo, have happened on my weapon as well?

What are the chances that at the bottom of my ammo can all the ammo that would be overgassed grouped together and happened to fall into his hands when he grabbed to load than mine?

I'm not trying to say anything bad against BCM or anything of the like. I love their gear, but it just seems like it should have happened on mine as well ya know?

[caelumatra]

I'd also like to reiterate that his weapon extracts in the 2 oclock range and mine in the 430-5 oclock range. Shooting the same exact ammo.

Does this indicate that it IS overgassed?
And if so why is it overgassed on his and not mine?

[hammonje]

No, the rifles have numerous subtle differences that cause extracted cases to land in a different pattern.

You issue could be in the chambers. Blown primers are due to overpressured rounds. The differences observed can be due to differences in the chambers of the rifle. How they are cut???? Perhaps one is more generous than the other. Blown primers can also be due to too much headspace. Measure the cases and see if the one's from the DPMS are longer than the one's from your rifle. Have the headpsace checked. If the chamber is too generous than the primers can back out. Conversely if the chamber is too small than this could also be a symptom and cause over-pressure.

I am a longtime reloader and service rifleman. This would be my diagnosis, but I need data from the extracted cases from each rifle.

[JSantoro]

As for the whole o'clock thing, if, other than the popped primers, your weapons are cycling reliably, you don't really have a problem. All you have is an "the little piles of brass aren't immediately adjacent to one another" problem. So, move over and pick the things up, or use one person for each pile. You're taking a rough diagnostic indicator for cycling problems and turning it into a symptom. That's like running hills for 6 miles, then thinking to yourself "Hot forehead. Runny nose. ****sticks, I have the flu!"

Table that.

First things first: Procure and fire another ammo brand/type for your buddy's rifle. See what happens.

[caelumatra]

That's like running hills for 6 miles, then thinking to yourself "Hot forehead. Runny nose. ****sticks, I have the flu!"

:sarcastic:


First things first: Procure and fire another ammo brand/type for your buddy's rifle. See what happens.

I will do this. I just didn't immediately think it was the ammo since it wasn't having the same malf on my rifle

As well as measure the cases. They're at his house as we reload as well and I'll have him post the measurements here.

Also, both barrels and bolts from both our rifles are BCM. If there was any confusion to the contrary

[hammonje]

In all likelihood it is not the ammo, but the chamber or headspace.

Maybe his chamber wasn't finish reamed sufficiently or too much.

[Iraqgunz]

Try some other ammo and another weapon. There is a possibility that the barrel is jacked up so I would consider contacting BCM and talk with them.

[cz7]

It's not the rifle, it's the AMMO...

it was both ammo and weapon- dpms had a 223 chamber and lake city ammo ........i would check the head space and lot of ammo for recalls..

[Low Drag]

As others have said it is most likely the ammo.

Can you measure the primer hole on one with a popped primer? I had a batch of M855 clone a few years back that popped primers. They where not over presure, rather the primer hold was .177" Vs .175" other ammo.

I got some of that brass mixed up with my reloading stuff and it really jacked me around. It cost me a number of malfuncitons at a Magpul class.

[usmcamp0811]

I just measured one of the primer pockets and it measured about .173"-.174"

just some more information the primers did not appear to be flattening at all, nor were they pierced all the way through, they looked just like every other spent primer that my reloading press pushes out. Could this problem at all be caused by the lower receiver? That's the only thing that we didn't change out.

[ForTehNguyen]

bad primer pockets or bad primer crimps?

[usmcamp0811]

I bought some 77g stuff before and it was pretty good stuff. I did have one round out of 200 pop its primer out though.

http://www.calguns.net/calgunforum/showthread.php?t=71912

Was just doing some internet research on this and ran across this.