Annoying problem with PTR...

[ralph]

I've been having a problem with my PTR. I've been using my reloads (using unfired RA 62 brass, 147 gr bullets) case gage used to inspect loaded rounds. Anyway, The problem is I'm getting a feeding problem, the empty case will eject, but the next round will not get fed, it'll get run over by the bolt/bolt carrier and smashed up..This usually happens on about the 16th/17th round with a variety of mags, HK, steel, aluminium, brand new FMP mags. Bolt gap is .010,and has held steady at that point, rifle was flawless for the first 600 rnds or so then started doing this, I also noticed it has some side to side play in the mag when it's in the mag well and some forward and back play as well, Normal?? Extractor cannot be moved with my hands, it seems very tight, Ejector looks like it sits high enough (almost touches the bolt head) and does not appear to be bent up or excessively worn. Any ideas??? I'd really like to get this thing running 100% O

[navarro]

I suspect the powder you are using has stubbornly built up undetected carbon in the flutes. A major chamber scrub and dry swab after, might be a good thing to start with.
If it is a JLD or PTR built rifle, I doubt it is a mag wobble issue etc. Maybe, but doubtful.
Good for you about being satisfied with the rifle headspace settling at .010. That is a non issue I believe and refreshing to see. Good luck!

[Shattered Mind]

You say the 15/17th round gets ridden over and smashed up. Does the smash up start all the way back to the rim or somewhere midway up on the shell?

[AviatorDave]

Interesting. I was going to say weak mag springs, but since you've already tried a bunch of different mags that likely rules that out.

Have you tried different ammo, maybe some factory loads? I'm wondering if perhaps you're using a light powder load that doesn't have enough pressure to push the carrier all the way back, or maybe a strong one that pushes it back so fast that it's returning faster than normal?

Just brain dumping here.

It just seems like it's somehow got to be related to an almost empty magazine, when the remaining rounds aren't being pushed up as quickly due to the full spring extension. It seems like if it always fails about the same time, you could load up a bunch of mags, and shoot out only 14 rounds from each one. Then see if you swap and use all the now partially loaded mags if you start getting failures. It might help narrow it down to something caused not necessarily by weak springs, but by the reduced magazine spring tension combined with some other issue.

[Shattered Mind]

Have you tried different ammo, maybe some factory loads?

I'm thinkin' ammo problem, too. He did mention he was using reloads. It's possible to get a weak charge and the bolt is only going half way back and "just" grabbing enough brass to slam it forward into the trunnion. and ride over it into battery.

[stubbicatt]

I'm going with the clogged flutes.

I shot a bunch of that brass RA61- 62 etc., and it had asphalt sealant in the case necks, which came out after the first firing, but that doesn't help so much DURING the first firing.

Maybe go ahead and buy a chamber flute cleaning brush and see if that improves matters.

[shellholder]

I would clean the chamber flutes. The powder you use in your reloads can be suspect also. Check your loading manual, there are many powders suitable fo 308's but only a few that have the correct burn rate for self loaders.

[ralph]

Okay;
I kept some of the smashed rounds..6 of them, on 3 the smash up starts at the base of the shoulder of the case on 2 others the smash up starts about a 1/4" down from the shoulder and on one the smash up is in the middle of the case,

Powders used were...IMR 4895 and Hogden BLC 2 the last 20 rounds shot with the BLC2 were close to max, the IMR loads were 42gr only other ammo(before I started loading .308) shot through this rifle was some S.A. surplus about 300rnds. The rest of the ammo (aout 700rnds) were my reloads.

[shellholder]

I will check in my loading manuals and records tomorrow to see if you are using the right powders. I haven't loaded 308's in a while and can't remember what the best powders to use are. My manuals are in my shop behind my home and right now it is storming like the dickens.

[tmbrwulf]

I had a ptr with some feed issues. In my case the hanger that keeps the clip locked in had some play in it. There were surplus clips in my rotation the hung a little lower than others. On my smashed bullets (mil-surp) you could see where the carrier would would miss at the back of the bullet and leave a mark from the base to the shoulder . Than the bolt carrier dented the brass pretty bad. Good luck . Let us know what you find.
Thanks'