AR Sponsor
Posted: 12/27/2011 6:53:21 PM EDT
|
So I've been having some issues with my AR lately and me, nor my buddies who are more experienced with ARs than I, cant really put a finger on it. So heres the low down: Bushmaster XM-15. 16" barrel and came from the factory with an A2 stock. (A2 shorty model, has fixed carry handle). Came into my possession relatively brand new. First day i took it out, ran about 300 rounds through flawlessly. Purchased and installed the Magpul MOE furniture kit (fore end, grip, and adjustable stock, with carbine length buffer assembly). Now my rifle is a one shot wonder. It either wont strip the next round from the mag, or the round gets jammed all cock-eyed in the chamber, wedged by the bolt. My buddy put his upper reciever on my lower and it worked fine. Not a lube issue, as my upper was well oiled and tested during troubleshooting. And the rifle is clean, before firing the first round. So whats the deal? Is it the carbine buffer assembly messing with it? With everything we did to get to work, the only thing left for me to assume is its a gas issue. Ive yet to install the old A2 stock back on and try it out then, I have a hunch that will cure it, but maybe not. And if that is the cure, what are my options for still using the Magpul stock. I was under the impression that a buffer is a buffer, aside from the milspec to commercial sizing and rifle to carbine length. Any input is greatly apprecieated.
Thanks! |
|
When you pull the CH all the way back is the bolt face behind, flush, or still in the ejection port a little bit? Have you determined if it's short cycling? Load 1 round in a magazine, charge it and fire it. Does the bolt lock back? Does the CH feel smooth when pulling all the way back? |
|
http://heavybuffers.com/reference.html Measure and compare your to these.This is all i got. but my bet is wrong buffer spring or buffer.YMMV  |
|
Quoted: "Purchased and installed the Magpul MOE furniture kit (fore end, grip, Could it be that you are using the A2 stock original screw which is longer and it's hitting the buffer. Check the plastic portion of your buffer for a screw dent. and adjustable stock, with carbine length buffer assembly). Now my rifle is a one shot wonder." |
|
you said you tried another guys upper on your rifle and it worked fine. I suggest placing your upper on their lower and see if you have the same problems, if so, you know it's tied to your upper. From there you diagnose further.
Good luck, hopefully it's just something simple like a magazine! |
|
Quoted:
When you pull the CH all the way back is the bolt face behind, flush, or still in the ejection port a little bit? Have you determined if it's short cycling? Load 1 round in a magazine, charge it and fire it. Does the bolt lock back? Does the CH feel smooth when pulling all the way back? the bolt goes all the way back in the action. thats not the issue, plus the the bcg operates smoothly. took a measurement of my old stock spring to my new one. the a2 spring measures at 12 3/4" while the carbine one i installed is 11 1/4". |
|
Same ammo before and after? Sounds like short stroking with weak ammo.
Check that the gas block is still secured and lined up properly. Basically, start from the point it goes bang to the fresh round being in place one step at a time. Tried different magazines, different bcg, different buffer... Obviously the suggestion to try your upper on someone else's lower is a great place to start once you give it a complete going over for loose or not aligned parts. |
|
I was one of the friends shooting with the OP when this was all happening. We didn't have another lower handy to try out at the time. The upper we used was a rifle length gas system and the OP's is a carbine length. This led me to believe that the buffer may not be heavy enough and the bolt was cycling faster than the mags could keep up. Is this a plausible theory? I believe he was using thermold mags, but if I remember correctly, we tried using a USGI mag as well and the issue persisted.
Ammo was Silver Bear .223, which could result in short stroking if underpowered, but has not been problematic in the past. Checking the gas key could be a good idea too. |
AR Sponsor