AR15 failing to put the extractor around the rim as the bolt grabs the round

[Kindrox]

When I shoot my AR15 I usually use an old Colt 20 round mag and usually only load 5 rounds at a time. I have not had any feeding problems with that. A friend shot it Sunday and loaded the mag full. At that the gun failed to go into battery and failed to shoot. Turns out the problem was the round was not clipping into the extractor. When I pulled the bolt back the round was staying in the chamber.

Fortunately by holding the gun straight up and shaking the round simply fell back out, but the problem happened every time the 20 round mag was pretty full of ammo. I didn’t have another mag with me to try.

Only by having about 5 or less rounds in the mag could we get on with shooting.

The gun is relatively new with only a few hundred rounds down the pipe. And it was cleaned and well oiled after the last time I went shooting so I don’t know what the issue is.

Any ideas?

 

[Jorg Nysgerrig]

I would try another magazine first. Did you mess with the extractor when you cleaned it?

 

[dewage83]

I had the same problem with an Ar just bought/ put together. I have not yet ruled out any possibilities of reasoning for this but I was quite upset. Im not sure but the mag folower could have a part in this, although I heard the colt's use aluminum folowers.

 

[Onmilo]

Failure to extract round from chamber is normally caused by:
Extractor spring may have failed or broken.
Carbon/brass fouling impacted in extractor recess.
Chamber is carbon fouled, may need to be scrubbed clean with a chamber brush and solvent.

The failure to fully feed the cartridge is probably due to the chamber being carbon fouled but faulty feed lips on the magazine could cause that problem too.

The number of rounds fired has nothing to do with the issues.
A hundred rounds of low quality ammunition can carbon foul the best rifle.

 

[Kindrox]

Failure to extract round from chamber is normally caused by:

My problem is different. It is not failing to extract from the chamber. The extractor never gets around the rim of the case in the first place.

My Colt mag has an aluminum follower. Other than the tension of the mag spring causing the bolt to have a little more work to strip a round, I am not sure if the mag could cause the extractor to fail to clip onto the rim of the round.

Did you mess with the extractor when you cleaned it?

I don't think so. I actually have not disassembled the extractor portion of the bolt, just scrubed around it.

 

[wanderinwalker]

It sounds to me like the full magazine offers too much drag on your BCG. There is not enough energy left from the bolt ramming forward to cam the extractor over the rim of the cartridge. The AR is a push-feed (for lack of a better word) so the extractor doesn't engage the cartridge until the last phase of lock-up.

Try another magazine. You might need a new recoil/buffer spring. But the mag will be easier to check first. You may also find better results with short-loaded mags, which would explain why you never noticed it when loading 5 rounds at a time.

 

[Kindrox]

Try another magazine. You might need a new recoil/buffer spring. But the mag will be easier to check first. You may also find better results with short-loaded mags, which would explain why you never noticed it when loading 5 rounds at a time.

The next time I go to the range I'll bring a bunch. If not the mag is the problem in the recoild spring (feels like "normal" spring resistance) or in the extractor?

I have heard of a "clam shell" extractor. Is it good? Do you need a new bolt to use it?

 

[Coronach]

1. Try a new mag. Easiest solution. Actually, try many new mags. As many as you can. If the gun has problems with more than one of them when loaded full, your problem is probably not the mag, it's the gun.

2. Check your BCG and locking lugs area of the receiver for fouling. You should not have appreciable gunk in there with a low round count and a new gun, but I'd hate to dig out the buffer spring if the problem is crud in the action. This is probably not the problem, but check it anyway. While you're in there, look for odd wear patterns or signs of a problem (kinda hard to quantify, but if you see an area worn shiny or visible cracks, you probably have a problem). Take some pictures of the BCG and post them. We may see something wrong that you don't.

3. Check your buffer spring. Next easiest solution. If it's not generating enough oomph, your gun won't go fully into battery when confronted with the drag induced by a fully-loaded magazine.

Don't fiddle with replacing stuff in the BCG just yet. No need to mess with that if the mag or buffer spring are the culprits.

Who made the gun, and what ammo are you using?

Mike

 

[Tarvis]

First guess: magazine/ammo combination, mostly the magazine
Second guess: extractor issues which could possibly (somehow) be amplified by the magazine

It sounds to me like the full magazine offers too much drag on your BCG. There is not enough energy left from the bolt ramming forward to cam the extractor over the rim of the cartridge.

That's what I was thinking at first, but when the bolt locks, it should still put enough pressure on the case head. If it didn't, there must be a really tight tolerance between the extractor and the case head. If the bolt is fully locking and the extractor isn't hitting the rim, there is something you're not seeing. Also, if the problem only occurs when you use a full colt mag that is well worn, bells should be ringing.

Could also be an out of spec extractor, I suppose, but it would FTE without regard to the magazine.

 

[Kindrox]

The upper is Bushmaster with a RRA bolt assemble. I purchased a fully-assembled upper and lower, and put them together. The range I shoot at is no-FMJ so I have been shooting soft points from Dallas Reloading. I know it is not factory ammo but the have a good local reputation. I have had problems with Wolf in this gun failing to cycle the action.

The 20 round mags have most of the finish worn off of them. Is just a new mag spring what is called for if it is a mag issue?

I won't get back to the range for a bit so I will start with a more detailed examination and pictures.

 

[strat81]

Does it do this if you load the mag with 18 rounds? Many AR mags are picky about being loaded to max capacity.

 

[Tarvis]

Some can be finicky with a full mag but that should have no bearing on extraction. I would call whoever you got the upper from and see what they have to say. If they have heard of the problem with their rifles before I'm sure they know how to fix it or what you did wrong.

 

[rcmodel]

It is unlikely it is the mag unless someone put a new extra-power spring in it.
Or the feed lips are very badly bent in.

If the old mag with the finish worn off has the original spring in it, it would be too weak by now if anything.

If the release notch is worn it would not put as much upward pressure on the bolt carrier as it once did.

If it never worked right, someone would have mashed it flat way before the finish wore off!

I'd suggest:
* Lube the the snot out of the bolt carrier.
* Remove & Clean the extractor. Make sure the spring and rubber buffer are installed correctly in the extractor. (Snapped in place in the pocket)
* Make sure the ejector pin is spring loaded & free to move in & out of the bolt face. Wouldn't hurt to take it out & clean it too.

Are you easing the bolt down with the charge handle to load it initially?
Operator error!
* Lock the bolt back, insert the loaded mag, and hit the bolt release. Let'R slam shut like it's supposed too.
* Never hurts to whack the FA a smack on the first round out of a full mag either.

rcmodel

 

[strat81]

Some can be finicky with a full mag but that should have no bearing on extraction. I would call whoever you got the upper from and see what they have to say. If they have heard of the problem with their rifles before I'm sure they know how to fix it or what you did wrong.

If the rounds in the mag are pressing heavily on the bolt carrier, it can slow it down too much to the point that the extractor will never get a chance to get around the case rim.

 

[Hokkmike]

It is aggravating. AR's tend to be finicky lot. I can't add to ideas suggested but I can empathize.

 

[rcmodel]

AR's tend to be finicky lot.

Actually, they don't, if they were a quality made AR in the first place. My 40 year old Colt AR Carbine has never once skipped a beat!

Unfortunately, there are a heck of a lot of sub-standard AR's, and sub-standard AR parts, and a heck of a lot of really crappy ammo for them floating around, with more being made every day!

rcmodel

 

[Kindrox]

If the rounds in the mag are pressing heavily on the bolt carrier, it can slow it down too much to the point that the extractor will never get a chance to get around the case rim.

The problem was there even with 15 rounds in the mag. I was not using the bolt release but I do simply let go of the charging handle.

I just realized I don't need to go to the range to work the problem as the whole issue is getting the extractor to clip over a round. That I can work on at home.

The upper is from PKFirearms. If another mag doesn't help then I will try a deep clean on the extractor, looking for problems in the locking lugs as also suggested, and then calling.

I have access to another, even newer AR (never shot) I can compare to.

I think there is not much more to do until I am home and can look things over and try different things.

 

[rcmodel]

I was not using the bolt release but I do simply let go of the charging handle.

That right there might be your problem!

The charge handle adds extra weight & friction the bolt carrier / buffer spring has to make up for. That slows the bolt carrier down to a certain extent.

Use the bolt release and see if that works.

rcmodel

 

[Kindrox]

Well the rifle is frustrating me now. I can't recreate the problem with the same ammo and same mag. I tried other ammo and other full mags (20 and 30 rounders) and still nothing.

But I do know to shoot with full mags now and to use the bolt release.

Updated:

Ok I think I found the problem. I disassembled the rifle and a crushed small rifle primer fell out of the action. I don't know where exactly it got jammed into but there probably arn't a lot of places one can get jammed into where it won't cause problems.

Where ever it was, it got mashed up pretty good. Maybe that is why military rounds have crimped primers?