Strange malfunction - Possible extractor/ammunition issues?

[mechelaar]

I was out shooting and all of a sudden, with the hammer back, my trigger won't move and my safety was stuck. I end up having to unload, open up my rifle, and shake it upside down. Something shiny falls out. My safety still felt like it was grinding so I slapped the side of the lower a couple of times. Suddenly everything works as it should.

I had something similar happen once before due to a popped primer, or so I had assumed at the time. I started checking my brass. No missing primers, but a lot of the brass was seriously chewed up. Fast forward to when I'm home. I popped out the trigger, hammer, and safety. They were all covered in brass shavings, dust, and a couple actual chunks. The inside of my lower looked like the floor of a machine shop. Small pieces of sheared off brass everywhere. This concerns me. The gun is still pretty new, around 500 rounds. The fact that it has had two critical malfunctions that needed the rifle to be broken apart to get it back running makes me less than pleased.

At this point, I have two thoughts. First, I am wondering if the extractor is too strong. Maybe go with a blue insert? I'm also wondering if it is an ammo issue. The brass that was chewed up the worst was Prvi M193. The rifle has also fired XM193, Hornady LE 5.56 SP, and Speer Gold Dot .223. The Hornady was not chewed up at all. I never checked the XM193 or the Speer. Also, the I fired some of the Prvi through one of my other rifles (BCM Middy with BCM BCG). It also was chewing the brass a little, but not as bad.

The rifle is configured as follows:
LMT factory lower with H buffer
LMT 14.5" factory upper w/ perm muzzle device
BCM BCG without o-ring (appears to have originally been CMT)

Any thoughts?:confused:

[mechelaar]

Anybody? :(

I'm just trying to figure out why I'm chewing up brass to the point that it is jamming up my FCG.

[Heavy Metal]

Pictures of the brass and bolt face would be nice. Please use your macro setting.

[mechelaar]

Here is the bolt face and extractor. My buddy grabbed all the brass, so I'll have to make another range trip for that. I tried to include an illustration of what it looks like. Looking at the casing from the rear, there were two torn up areas were right along the edge of the case rim (illustrated in red). On some of the rounds, the edge of the rim was actually punched all the way through. It looks like the extractor was pulling hard enough on the rim to damage it.

I am hoping that maybe I just got a batch of ammo with weak brass, since it was happening, to some degree, with both rifles. I never noticed it on any other ammo, but I wasn't really looking for it either. Like I said, the Hornady I shot the same day was intact.

http://s694.photobucket.com/albums/vv305/mechelaar/Picture004.jpg
http://s694.photobucket.com/albums/vv305/mechelaar/Picture003.jpg
http://s694.photobucket.com/albums/vv305/mechelaar/bullet.jpg

[Heavy Metal]

It almost sounds like you are having hard extraction. Who built your barrel?

[mechelaar]

It almost sounds like you are having hard extraction. Who built your barrel?

The barrel is LMT. Are you thinking the chamber might be tight? That would be disappointing. What would be the best way to check without actually using a reamer?

Could it be that the ammo was over pressured? The BCM middy was also causing slight deformation of the brass (but nothing as extreme as the LMT carbine).

[Iraqgunz]

I am fairly certain it is an ammo issue. I have seen this happen before with PP ammo and I wouldn't rule out that you may have some popped primers. I would only use PP for training or TEOTWAWKI.

[mechelaar]

Thanks for the advice guys. I hope Iraqgunz is right and it is the ammo. Anything else I can check to confirm?

The batch of Prvi I have is gone, otherwise I would put it through some more rifles to see if I get similar results. I'll try some other type of 5.56 soon to see if I'm having trouble with all NATO pressured ammo. Although the Hornady is marked 5.56, I'm not 100% positive it is actually pressured as such.

Oh, and the PP is just for cheap training/play. However, if using PP on occasion is going to make my rifle unreliable, it's not worth the money.

[Eric]

http://s694.photobucket.com/albums/vv305/mechelaar/Picture003.jpg

Maybe it's just the angle, but your extractor looks to be in the wrong position. Almost like it's too short and sitting too low.

Do you have a different extractor to drop in?

[Bones357]

Maybe it's just the angle, but your extractor looks to be in the wrong position. Almost like it's too short and sitting too low.

Do you have a different extractor to drop in?

That was my first thought when I saw it, too.:confused:

[medic15al]

Was it a primer that fell out? A popped primer can lock the action up.

[mechelaar]

Maybe it's just the angle, but your extractor looks to be in the wrong position. Almost like it's too short and sitting too low.

Do you have a different extractor to drop in?

I think it is the angle. I compared it to a couple of other bolts (another BCM and a LMT). Eyeballing it, I would say that the extractor in question is slightly shorter than the LMT, but about the same as the other BCM.


Was it a primer that fell out? A popped primer can lock the action up.

That's what I had originally assumed. I checked the brass from that day and there were no missing primers, just the gouges in the rim. I suppose I could have blown a primer some time ago and it just took a while to work its way into a critical area.