AR Sponsor
Posted: 3/28/2010 3:29:31 PM EDT
|
ALL NEW PARTS - Smith Wesson M&P lower, DPMS 7 1/2 Kitty Katt upper, full length buffer tube assembly and inards from Model 1:
Took to range today and nothing but problems. Would only fire one round, it would eject the empty and fail to feed next round. Ammo tried was PMC, Federal XM193, Remington and even Wolf. No isssue with ejecting at all. Shot about 150 rounds today and the most fired shots I got off was 2, before it would go click and be empty. A few times it would double feed. Swapped mags from standard metal to PMags and no change. Swapped out complete bolt carrier assembly and still did not fix it. I am thinking it is having some type of gas issue. Where do I start? |
|
Whenever I test a new build, I always load a single round in a magazine for the first few shots to make sure it cycles. If it locks the bolt back, then you know it's good to go.
If it doesn't then you have a gas problem, or (in the case of buying a complete upper from a reputable dealer) you probably have a buffer problem. You can try a lighter buffer. To trouble shoot the gas issue, start with the gas key. Make sure it's tight and make sure it's staked properly. Look at the gas block and the gas tube. Check for soot which indicate a gas leak. Then you're into taking the gas block off the barrel and measuring the gas port size, as well as inspecting the gas tube and gas block itself. |
| Since you swapped B/C's I would look at the gas tube/block/and gas port. I've had a gas tube that somehow got some red locktite in it. I've never used a full length buffer and spring in my SBR's so I don't know if the extra spring length would cause problems or not. I do know the full length buffer tube, spring and buffer are designed for a rifle length barrel/gas system. |
| I think it is fixed!! Took pistol to friend who is helping me along. First we tried easy things, Tried 3 different buffer weights. No change! Tried M16 heavy bolt carrier, No change! Changed gas rings and nothing. So gas tube time it was. Removed tube and all was clear, noticed how small the hole was in the barrel. Called DPMS to inquire the hole size for the Kitty Katt 7 1/2. They said all DPMS barrels are drilled .055. They also made mention if you shoot it suppressed it will work fine. So suppressed we tried and ran fine all day. But I am not keeping a suppressor on this one. So Asked DPMS about going larger with the hole. We discussed hole sizes. I was afraid I would go too big, which I was told if I did, worse case if I do, is switch to heavy buffer to compensate too large a hole. So time to drill new hole. Went with .078 and time to test fire. Worked perfect so far, only was able to shoot a couple rounds, but it cycled perfect and bolt locked back. None of which it did the other day. So I think it is fixed and I am back to being happy again. I did more reading about hole sizes and see that most guys run even a bigger hole than I did. Some are as big as .090's, I am sticking with .078 for now and see if any issues develop. Thanks guys for you input. Tim |
AR Sponsor