New YHM AR extraction problem

[r3captain]

Recently purchased a YHM upper in 5.56 and about every 5-10 rounds the extractor pulls past the rim, leaving some tasty chew marks, causing a stove pipe. I had the same type of problem with and old mini-14 from shooting 5.56 ammo in a .223 chamber. I'm using 3 quality mags and Winchester, white box, ammo so I'm sure that's not the issue. I'm new to the AR world and don't know if there is an adjustment or something else I may be overlooking. Thanks for any suggestions.

[Sky_DiveR]

Not sure if this is what you're talking about but if the extractor is pulling past the rim of the cartridge you may want to upgrade the extractor spring.

http://www.midwayusa.com/viewProduct/?productNumber=892652

[r3captain]

That might be the issue, but because the stuck rim has a bite taken out of it by the extractor, it seems like the casing is just too tight. I'm sure it's not a good idea but a little light oil in the chamber sounds like it might cure it.

[sonnyt650]

Funny, I just came back from the range with my new YHM barrel which experienced an FTE every time. Same symptoms too: the ejector rim was torn off of several of them. I had to get the cleaning rod out and knock the fired case out because it was stuck in there maybe half the time. Did you have an issue with scratches on the brass? I reload and spend some time cleaning up my once-fired factory ammo, so I stopped after around twenty rounds rather than destroy more brass. I just scrubbed the chamber hoping it's gunk that caused too much friction when the brass expands, we'll see what happens I guess.

[r3captain]

Yep, you got it too. When it happened on my first trip to the range a week ago, I took it home and oiled the bolt real well and wiped it down. I then fed 20 or so rounds through it by just cycling the bolt each time with no problem and thought I was good to go. Next trip to the range the first magazine fed with no issues, but then it started acting up again. I'll try cleaning the chamber real well and see if maybe YHM had left some sort of goop in the chamber that is causing the problem. Do these things have a break in period of some sort?

[Sky_DiveR]

Sorry, misunderstood your problem. So the case is stuck in the chamber with a piece of the rim torn off? Could be your chamber is just alittle bit rough or your timing is just a touch off. Try polishing the chamber with some Flitz polish.

Some pics of the ammo and alittle more info on the configuration of your rifle might be helpful in actually diagnosing the problem. Also if you have done any mods or changed any parts. Don't forget what type of WWB ammo you are using (ie: 5.56 or 223)

[sonnyt650]

Do these things have a break in period of some sort?

Not really, especially if the chamber is chrome-lined which is an incredibly hard surface which resists wear and that won't be easy to clean up . I did scrub the barrel bore prior to shooting but not the chamber, and after shooting there was some dirt in the chamber even though it was tightly sealed by the brass even after firing. I'm hoping YHM didn't chrome a rough chamber or do a second-rate job of chrome lining, but the jury is still out.

There are some wear bits in the mechanism such as the engaging/sliding parts of the bolt lugs and carrier which need oil or grease (from the description you got those I'll say), and the rings on the bolt should be oiled through the little hole in the carrier. But like any firearm the chamber is supposed to be free of oil and grease so the brass can grab the chamber wall while firing since the case acts like a gasket that seals the bolt and chamber.

My upper has an Adams Arms piston kit so I was able to experiment some. Using the gas regulation knob I disabled the automatic extraction and shot once: this was another instance where I had to use the cleaning rod to remove the case. After maximum pressure subsides the case shrinks back some and so can be ejected. I'm guessing the grip from the rough surface is preventing extraction from my barrel. I'm pretty sure the chamber is the issue for me, maybe for you too since it's also damaging the case rims. We'll see what happens since I really went at it while scrubbing the chamber and will continue to do so until the next range session.

[r3captain]

Just got home from a trip. I'll do some more investigation and let you know if I find anything unusual.

[bjl333]

Umm !! I've had my YHM Diamond Spectre upper for quite a while already with an estimate round count of about 1000. I've never experienced anything wrong with my upper. a lot of the rounds are from friends I take along to the range. I hope you'll get you problem solved, my YHM is one of my fav rifle.

[halon101]

i had this problem on a bushmaster upper.
i already had the bcm extractor upgrade on there but at least once a mag i had a stove pipe. i was pissed because i had another upper shoot fine on the lower.
the rim of my case was exactly like you described, extractor pulled off. i tried alot of different ammo. then i red that it was my buffer. the other upper that worked fine was a midlenth gas system. the bushy was a carbine. it wasnt even the upper.
i bought an H2 heavy buffer from riflegear and the upper shoots beautifully.

[halon101]

the theory behind the heavy buffer is that it will slow down the bolt. and slow down the cyclic rate of your gun. you wont really notice that. but you might notice the reduction in recoil.
if you go too heavy on your buffer you will start to short cycle.

[r3captain]

Okay, the heavy buffer is making a lot of sense. The rest of my story is that my AR had originally come with a 20" Noveske chambered in 6.8 SPC. I wanted to be able to shoot ammo that cost less than $1 a round and was under the impression that it was just a swap of uppers to go to 5.56. Found this article and although long, is quite interesting. http://www.ar15barrels.com/prod/operation.shtml Looks like I'll be ordering up that heavy buffer. Thanks guys!

[sonnyt650]

That article is a good read, now I have more ability to diagnose normal FTEs. It reads like you've found a potential culprit with the buffer, though realize also there are two different lengths of buffer with the H2s available only in carbine length AFAIK.

For my situation I should add: when I used the cleaning rod to knock the brass out I had to "wind up" some and whack it out of there with a few hits. In the process I trashed the smooth finish on my aluminum Dewey cleaning rod, though that part of the length is in the chamber guide when the rod is used for cleaning so it should be ok. *edit* Or not after thinking about it some more. Damn.

[r3captain]

Sorry to hear about your cleaning rod. Did you notice if your barrel was extra dirty for not using it much? I had read that extra gas can get in with too light of a buffer and my barrel was full of nasty green fouling after only about 60 rounds. Anyway, I ordered a heavy buffer and hopefully I'll know in a week or so if it does the trick.

[Sky_DiveR]

If you have some lead shot (or empty some shotgun shells) you can make your own. Just punch out the pin, pull off the plastic plug, and dump out the weights and spacers that are in there. Pour in the shot and replace the plug. Easy, cheesy. You can also melt down some old fishing sinkers if you don't have some lead shot but it's not as adjustable as using shot that you can add or remove to adjust the weight. Melted lead will weigh more if you fill it up.