This +1Originally Posted by TomMcC
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This +1
RLTW
“What’s New” button, but without GD: https://www.m4carbine.net/search.php...new&exclude=60 , courtesy of ST911.
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
Senior Member
If the bolt traveled far enough to strip a new round, but didn’t eject the old, would that not be an ejector issue?
Senior Member
Sounds pretty similar to an issue I had a few years back with a newly assembled carbine that had a BCM BCG in it. The general consensus at the time was that the extractor was slipping off the rim during extraction. This was during a time when BCM apparently had a bad batch of extractor springs go out. Changing the extractor spring/insert to the Colt gold-colored one corrected the issue.
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It’s hard for me to visualize what happened from reading the OP, but what TomMcC suggested is cleaning the chamber, then changing extractor, extractor spring, or ejector spring. When I deal with wonky crap like this, I just clean it up and swap all three at the same time. It sounds like its one of those three.
RLTW
“What’s New” button, but without GD: https://www.m4carbine.net/search.php...new&exclude=60 , courtesy of ST911.
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
Member
Totally agree with sscs comment on cleaning. I've shot countless rounds of dirty Barnaul ammo - I don't think it's the devil some people make it out to be - but it's a must that you keep your rifle clean.
A short story... I once did an experiment of not cleaning/lubing one rifle for a long time. Probably shot about 1000 rounds of Russian steel case in that time. One range trip, I noticed the BCG getting a bit sticky although it shot fine for the session. Put rifle back in safe. Around 3 weeks later I went to get it out again, and damn me if the BCG wasn't locked up solid on an empty chamber! Some judicious 'mortaring' later, and I finally got it freed off and at that point gave the rifle my usual thorough Army style cleaning and all smoothness was restored. It was as if the crud had got to the point where it had some 'set up' while it was in the safe.
Member
As I mentioned yesterday by the time I made my post I had already done what I thought would fix the problem. Just got back from shooting that rifle again and it seems to have remedied the malfunction.
My initial thought was the same as most; that it was an extractor issue. It seemed to me that the extractor was slipping off the rim before the casing was pulled all the way out. I took apart the extractor and found the standard spring with a black insert. I have BCM bolt upgrade kits in the parts box so I added the o-ring donut to the extractor spring assembly and put the rifle back together. Again, after going back out today to test, the o-ring seems to have taken care of the issue as we had no further stoppages today.
I know that IG was not a fan of the donut but since I don't have any Sprinco or Colt extractor springs on hand this will work until I can get some ordered and swap them out.
Last edited by sva01; 06-28-20 at 13:02.
Member
If the extractor slipped off then the case won’t be extracted far enough for the ejector to come into play.
The extractor has to pull the case far enough to clear the chamber and to present the case mouth to the ejection port. As the case mouth leaves the champer, the ejector is able to start pushing it towards the side of the upper where the ejection port is so that when the case mouth hits the ejection port opening it will fling it clear.
Senior Member
I understand how it works, I just was under the impression that the spent case was still being held by the extractor claw through the cycle of operation and figured he had an ejector issue that prevented it from kicking the round out.
Senior Member
Yeah, the donut has the effect of ratcheting up the spring pressure. If the gun was working before without the donut, it's just indicative that your extractor spring is getting weak, but you probably knew all that already.
Member
Another possibility. Both the extractor and the ejector can be fine. If the bcg travels back but does not travel far enough for the case mouth to clear the receiver enough to be pushed out the port, when the bcg starts its forward motion the empty is pushed back into the chamber causing the appearance it was never extracted. As the bcg goes forward, since it did not go back far enough to catch the head of the next cartridge it rides up over the next cartridge, dragging it forward until it pushed up by the feed ramps. The bcg will then lodge on the case causing a dent in the case just before the shoulder. Usually this will not result in the bullet being set back.
If the bcg did go back far enough that it does catch the case properly and push it out of the magazine without the fired case having been fully extracted the bullet will probably be pushed into the barrel extension below the feed ramps and will be pushed back into the case mouth.
As described in the OP I would bet on a short stroke. Check the gas system for fouling and the carrier key for signs of leakage. Then a through cleaning.
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