Stuck in C Posted May 7, 2011 Share Posted May 7, 2011 I replaced the aluminum tube fore end on a Bushmaster V-Match (20" H-bar 5.56 barrel) with a JP/Viking Tactical one. At the same time I replaced the gas tube. Also, I changed the lower from an A2 stock to an adjustable carbine style stock. No other changes: same pinned gas block, BCG, etc. Ejection is now very weak, the spent case barely rolls out of the port. It still cycles 100% but I'm afraid it won't when it gets dirty. The carrier end of the new gas tube looks good (straight) and I can't feel any drag when hand cycling the bolt carrier. Is this likely a restriction somewhere else in the gas tube/gas block? The way the block is pinned on you really can't adjust its' position. Could this have anything to do with the new buffer? Link to comment Share on other sites More sharing options...
caspian guy Posted May 7, 2011 Share Posted May 7, 2011 (edited) If you load only 1 round in the magazine will it lock back when you shoot it dry? If not that may imply a problem with the gas system of some kind. The buffer and spring can impact cycling. Which carbine buffer did you use? Edited May 7, 2011 by caspian guy Link to comment Share on other sites More sharing options...
cardiackid Posted May 7, 2011 Share Posted May 7, 2011 Gotta be buffer/spring related. It's *almost* impossible to put a new gas tube in wrong if the gas block is non-adjustable, was never moved or rotated, and everything looks with the tube contact to the carrier key. I only say *almost* because there's always someone who will figure out how. I take it when you replaced the A2 stock with the carbine stock, you replaced the existing spring and buffer to carbine length as well? Does the buffer have anything stamped on the face of it? H, H2, H3 etc? Link to comment Share on other sites More sharing options...
cas Posted May 7, 2011 Share Posted May 7, 2011 (edited) You CAN put the gas tube on wrong. Besides upside down of course, I've seen someone get the pin in front of the tube and not through the hole. Somehow the tube was getting enough gas to function a little.. very very briefly. A couple of shots, until the gas tube apparently moved backwards and jammed inside the gas key. It caused a really strange malfunction, we could cycle the bolt part way by hand with lots of force. We found out the gas tube was reciprocating with the bolt... the gun had the epoxied on type FF tube so there was no good way to grab the tube (at the range) to free the two parts. We ended up yanking the whole tube out through the rear, a direction they don't like to go with that bend in the tube. Edited May 7, 2011 by cas Link to comment Share on other sites More sharing options...
cardiackid Posted May 7, 2011 Share Posted May 7, 2011 Haha - and there we have a perfect example of the *almost* impossible... yet entirely possible. I've heard of the missing the roll pin slot entirely, but I actually saw one gun where the owner/assembler/someone had actually drilled another hole in the tube for the roll pin because "it didn't line up correctly with the other hole" and proceeded to install it that way. Needless to say it didn't work. Link to comment Share on other sites More sharing options...
Stuck in C Posted May 9, 2011 Author Share Posted May 9, 2011 I was right: I shot a match Saturday and it short-stroked on the last mag of the last stage of the match when it was pretty dirty. I cleared it and fired the last 7 rounds ok. I did have to remove the gas block to install the forend. But, it is pinned in place with two channels drilled through the barrel so it is some what locked in position. The buttstock is a Rock River Arms that came as a kit with new spring and buffer. I'll look at the buffer to see if it is marked. What should I be looking for? I suppose I can re-install the A2 stock, spring, and buffer to see if that's the problem. Is there any way to check the gas tube? Link to comment Share on other sites More sharing options...
stik Posted May 10, 2011 Share Posted May 10, 2011 I think you may just have a stout recoil spring if it is brand new. Try leaving the rifle's bolt locked back while it is stored for a week or so to allow the spring to set a little and then go back and re-try it. I seriously doubt it is a gas flow issue with the gas tube or gas block. Link to comment Share on other sites More sharing options...
Aristotle Posted May 11, 2011 Share Posted May 11, 2011 (edited) Rifle length gas tube, FA carrier and too heavy of a buffer could slow that cyclic rate to the point of what you are describing. If you are running anything heavier than a H buffer, I'd suggest going to a lighter buffer. If the buffer is not stamped, which I see a ton that aren't, throw it on a postal scale. carbine- 2.8oz H- 3.9oz H2- 4.6 H3- 5.4 Also check to see if you aren't binding on the extension. I've seen bad/out of spec tubes do this as well. Check the inside of the buffer tube for any excessive wear. What kind of gas block is it? Check around the collar of the gas block to see if there is any excessive blow by. Another place to check is the gas key. It could have gotten tweaked somehow. Is it properly staked? Edited May 11, 2011 by Aristotle Link to comment Share on other sites More sharing options...
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