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Posted: 9/27/2002 1:24:34 PM EDT
As some may know, I purchased an Army M-261 .22lr conversion a couple weeks ago at a show. I then bought a used 1 in 14 upper to go with it and blocked off the Gas system. The accuracy from this system is excellent for a basic plinker. 2" at 50 yards, under an inch at .25 yards and at point of aim.

The problem I'm having is with reliability. I seem to be getting one or more jams per mag. As a training aid it is excellent. I can clear an AR jam faster than snot after this training. Over the last two days I have put about 1000 rounds through the rifle. I have been able to class these jams in two catagories. Failure to feed, and Failure to fully eject.

The failures to feed come with the nose of the round half crushing on the chamber mouth. There is what appears to be a small ramp on the chamber mouth. My thought is that deepening and lengthening this would help. About half a bullet width should do it. I have noticed this far more often with any sort of hollow point ammo. I tried several brands. I also tried the dreaded Thunderbolts and CCI Minimags. This problem was less prevelant with solid point ammo.

The second problem is more insideous. An empty cartridge casing get jammed between the bolt and the charging handle locking up the action. It appears that the round does not fully eject and bounces back into the chamber before the action can cycle. This one is hard to clear and usually requires partial disassembly. I think this is partially caused by the screws holding the rear unit in place loosening, loctite should fix that, but it has happened when the rear is secure.

Any opinions on fixes would be appreciated. I really love shooting my .22lr AR, but these reliability issues are becoming annoying.
Link Posted: 9/30/2002 8:51:49 AM EDT

Originally Posted By shotar:

The second problem is more insidious. An empty cartridge casing get jammed between the bolt and the charging handle locking up the action. It appears that the round does not fully eject and bounces back into the chamber before the action can cycle. This one is hard to clear and usually requires partial disassembly. I think this is partially caused by the screws holding the rear unit in place loosening, loctite should fix that, but it has happened when the rear is secure.

Any opinions on fixes would be appreciated. I really love shooting my .22lr AR, but these reliability issues are becoming annoying.



Since this has a fixed ejector, the extractor is probably losing
its grip on the rim. There is a little piece of spring steel wire opposite of the extractor that puts pressure on the case, helping it. This might not be exerting enough pressure or it could be loose where it is staked into the bolt.
Your feed problems might be related to the rim not getting all the way up into the boltface. The extractor hook might need to be tweaked, the firing pin might be protruding a bit, causing the rim to catch, or there could be some burrs on the boltface.

I'll look at it next time we get together at the range.
Link Posted: 9/30/2002 7:00:23 PM EDT
Thanks Waldo I appreciate it. I also ordered a couple of new mags for it today to see if that helps. It ran pretty well this weekend after I disassembled the mags, cleaned thoroughly and stretched the mag springs a bit. I also hosed down the extractor with CLP making sure to hit all the crevices. Accuracy was on par with a stock 1022 at both 50 and 100 yards. Very fun, but getting up at 6am to drive down to meet you guys was not in the cards this past Sunday. See ya soon.
Link Posted: 10/7/2002 6:56:10 AM EDT
[Last Edit: 10/7/2002 6:57:11 AM EDT by 223reg]
Dunno about this particular unit, but most of the Ceiner units badly need everything polished, to include the chamber and the breechface. I have had good luck with just using the Dremel cutoff wheel to slice a disk off of an approprite diameter nail, and use this shim under the extractor's coil spring. The resulting increased tension can be adjusted, by using different thicknesses of shim. Lipstick a few cases, and see if the extractor hook edge is actually touching the side of the BODY of the case(not the rim, now). If it's not, might try cutting away metal on the inside of the extractor body, until the hook edge just "kisses" the cases, then GENTLY remove a bit of the extractor hook, and I mean only about .005. Use a caliper to measure the hook, and a few strokes of a hand held stone at a time to modify it.
Link Posted: 10/8/2002 3:34:26 AM EDT
I developed the AR22 dedicated upper at CLE. The M-261 was chosen because it is robust and well designed. There are several things we do to the M-261 to make it function reliably. The biggest problem was failure of the bolt to close all the way and then the firing pin wouldn't make contact. Next was failure to feed.
First and formost, headspace the bolt! We have found the headspace excessive on all the military kits.
Second, that little hair spring opposite the extractor needs to be exactly 90 degrees when looking down at it from the top. Take it out and tweek it. If it is tighter than 90 there is too much pressure and looser it won't work.
Third, we take some coils off the extractor spring. I forget how many at the moment.
Fourth, stone a little radius on the corner of the bolt protusion that holds the bolt back so it dosn't try to cut a keyway in the top bullet in the magazine.
Fifth, we make a dedicated 1:16 Douglass Stainless Barrel that has all the adaptor features in place, but with much more precision than the adaptor. The adaptor is replaced with a special part that keeps the bolt together when it is out of the gun.
Finally, I have a quick and simple modification to the magazine that cured all my failure to feed problems.
Link Posted: 10/8/2002 4:17:25 PM EDT
Ray:

Thank you for your informative response. I have noticed the occaisional failure of the bolt to fully close. I have however only experienced this with damaged ammo. By that I mean it was mariginal and I forced it to chamber. New undamaged ammo chambers just fine.

I am curious about rounding the bottom protrusion on the bolt as I have noticed that the follower on my mags have what looks like tool marks, this could explain the marks. The wire thingy is straight at 90 degrees. I will check the extractor as this seems to be an area of concern. There is a problem with proper ejection. The only remaining problem seems to be rounds sometimes failing to fully eject and getting caught between the bolt and charging handle. I was just wondering what it would cost to take my kit and upper and make the conversion you mentioned less the douglass barrel?
Link Posted: 10/9/2002 6:19:20 PM EDT
Shotar,
The Compass Lake dedicated upper requires a barrel. It can't be done using the .223 barrel.
I have documented my magazine alteration and it can be found at:www.ray-vin.com/frcatalog.htm
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