ar 15 jamming

[Jackal]

I was shooting a friends ar-15, a stag model 1, and it jams periodically. I've deduced that it must be losing pressure somehow.

A spent casing will still be on the bolt face when a fresh round is stripped from the mag and loaded. This results in the spent casing preventing the new round from loading and there is a jam, the spent casing is on top of the new round and you must clear the rifle at that point by removing the mag, etc.

This isn't ever round, but out of 30 rounds the other day, the gun jammed probably 4 times.

Aside from the bolt gas rings, could there be another culprit? Note, the gas tube was pretty well cleaned up so I doubt it was something there.

[awfroadan]

The gas tube may be clean but is the rest of the gun? How about lube? Is it lubed? What kind of ammo is being used? Factory or reloads? Did you check the extractor and ejector springs to see if they were broken? Check all these things out.

[lilb93]

extractor.. from what i'm understanding of your situation

[Jackal]

The extractor spring looks fine, although it was dirty. The gas rings look fine and are not line up. The ejector still has force, although I did not manually inspect the spring...it seems normal by external inspection.

The gun probably does need to be lubed. Is there still a free (CLP?) offer on pafoa?

[Legion_Prime]

What ammo were you shooting? Check to see if it's short stroking. Insert a mag known to engage the bolt hold open, fire that round. Does the bolt stay locked back? If not you have a short stroking issue, try using some XM193 and see if the issue continues. If so you need to check for carbon around the gas block/tube indicating a leak. Also be sure to check the gas key, make sure there is no carbon buildup around the base indicating a leak and make sure that the bolts are properly staked. Check to see if there is any unusual/uneven wear on the end of the gas tube indicating misalignment. If it is not short stroking the ejector may be the issue. Normal lubrication should be a drop or two on it and then hook an EMPTY not live round on the extractor and push on the side of the case to depress the ejector and work the lube in. First step though should be to pull, clean and inspect it. Then reinstall and lube periodically as you would the rest of the gun. To check gas ring wear remove the firing pin and retainer and cam pin. Insert the bolt into the carrier to where the bolt lines up as you would normally to install the cam pin and set the bolt face down on a flat clean surface. The boltcarrier should not slide down onto the bolt, if it does you likely need new rings (or much less likely a new carrier). Even so I doubt that the rings would be so worn as to cause this issue, it is most likely a sticking ejector but you never know. Check these things out and let us know what ammo you're running.

[dodge]

Check and see what color insert is in the extractor. It should be a black one for a carbine. I ran into the same problem with my Stag Model 3 and bought a up grade kit for it. The kit had a black insert, a different spring and and o-ring. I also put a H2 buffer into it. Haven't had a problem since.

[Jackal]

Check and see what color insert is in the extractor. It should be a black one for a carbine. I ran into the same problem with my Stag Model 3 and bought a up grade kit for it. The kit had a black insert, a different spring and and o-ring. I also put a H2 buffer into it. Haven't had a problem since.

The piece underneath the spring is blue (pictured). Do you have a link to the kind of kit you are referring?

Ammo is brass cased stuff in white boxes, I think its mil-surp. It doesn't look inferior either way. Mags are crummy mil-surp's, gray metal, looks like aluminum with green followers.

I found some carbon buildup in the hole in the bolt carrier, the one directly under the bolt carrier key. I cleaned that out as it probably has been 1000 rounds since my friend cleaned it, since it was new actually.

Checking the ejector now. What are considered good quality ar mags?

[Legion_Prime]

Here is a link to the BCM Extractor Spring Upgrade Kit ($12 for 3 rather than the $5 1 pack)
http://www.bravocompanyusa.com/BCM-E...20%203pack.htm

Make sure the wide end of both the insert and spring go into the extractor and then the O-ring goes over that and then reassemble, be sure to use your man hands
Good quality mags are ANY PMAGS, TangoDown ARC magazines or any USGI AL manufactured by a .mil supplier such as OKAY, Center or Cooper Industries, Colt, Sanchez and others. I have had good luck with C Products magazines, others have had hit or miss experiences with them but their 6.5 Grendel and 6.8 SPC magazines are exceptional. Others have had good experiences with the Lancer magazines but I have not handled any personally so YMMV.

[synergy]

I was shooting a friends ar-15, a stag model 1, and it jams periodically. I've deduced that it must be losing pressure somehow.

A spent casing will still be on the bolt face when a fresh round is stripped from the mag and loaded. This results in the spent casing preventing the new round from loading and there is a jam, the spent casing is on top of the new round and you must clear the rifle at that point by removing the mag, etc.

This isn't ever round, but out of 30 rounds the other day, the gun jammed probably 4 times.

Aside from the bolt gas rings, could there be another culprit? Note, the gas tube was pretty well cleaned up so I doubt it was something there.

How many rounds through the gun? What kind of ammo where you shooting? How was it lubed?

As suggested, try some hotter loaded rounds, and see what happens.

A leaky gas block isn't all that common, lots of other things cause rifles/carbines to choke that are far more common...

Gas tubes don't get dirty shooting .223 or 5.56mm ammo. A carbine length gas system has gas in there at about 14k psi with each shot fired....what kind of gunk do you think is going to build up and stick in there under that kind of pressure?

Lube it well, try some xm193 or m855 ammo through it, with the good mag and see if it'll lock back...then let us know how it goes. If it still hangs up, try and snap some pics, they go a long way into solving these problems.

Also, read and heed some of the advice given here....
http://www.m4carbine.net/showthread.php?t=7376
This may be of use to you, as well...depending on how the above recommended test goes for you:
http://m4carbine.net/showthread.php?t=138

Good luck.

[Jackal]

Thanks for the links Synergy, I hadn't understood how complex of a rifle it was until reading those pages and the many other pages I was subsequently led to.

I'm partial to the AK platform myself, this does kind of make me appreciate the AK design a bit more. None of the issues and particular spec requirements of the AR seem to be an issue with the AK. The correct buffer tube and spring tension, ammo choice, mag choice, various staking requirements, and the extractor, none of them are potential AK problems.

In my mind, if the AR can out shoot an AK (which I believe it can) on the range then that is one thing. But if there are no parts to replace broken ones with, no time to clean the gun/no means to, and random jamming issues that could be attributed to one of several things, I don't see the real value in the platform in a true shtf scenario. Maybe I am missing the point?

I can hit a few inch group at 100 yards consistently with irons and my AK has never jammed and I don't think it will. It is simpler, easy to teach anyone how to use, cheaper, and more reliable. The AR is more elegant, more ergonomic, lighter, more accurate, more expensive (gun and ammo), more complicated to use and maintain. I don't see the benefit to the AR in a situation where someone with an EBR would actually need to use it, like some horrible shtf event.

Discuss, maybe I am over-simplifying the comparison.