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Posted: 1/16/2005 9:02:52 PM EDT
| I have an AR15 with a brand new 20" HBAR upper I bought complete from DPMS a few weeks ago and it is very unreliable. It fails to load a new round every couple of cycles or it will jam a round sideways and I have to help it by pulling the charging handle. People tell me this is short cycling because the bolt will be stuck out when the bolt carrier is all the way to the rear. I took my bolt/ bc and put it in my friend's gun and bumpfired about 80 rounds through it with no problems. The bolt/bc is ok. I put his bolt/bc in my gun and had the same problems as before. I have narrowed the problems down to my upper, something to do with the gas tube. I took the handguards off and there is some black powder build up at the very front. Is this normal? Should it be leaking there? I am not familiar with the purpose of the gas system either so I don't know where to look or what for. Does anyone know what I should do besides getting DPMS on the phone to complain? |
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Unless your running an A2/A1 stock buffer and spring in a collapsible M4 type stock, the bolt face should always travel past the back of the magazine. This can be viewed while rifle is unloaded and hand cycled. As to the black powder around the FSB, some leakage is normal, as to "how much", that's hard to tell over the internet. As upper is new and purchased from DPMS, the most common thing to do is contact them and return it for repair. You might want to view the www.ammo-oracle.com paying special attention to the 223 vs 5.56 chamber issues at the top there, just incase your rifle has a 223 chamber and your trying to feed it 5.56mm rounds, which can cause short-stroking. Good luck, Mike |
| I am using a 6 position stock I bought From RRA. I am using the spring that came with it. Should I try using a different spring? I have another stock that came with the lower, the old school 3 position stock. Maybe I should try the spring for that one. When I hand cycle the action the bolt will clear the magazine. It's just when I start shooting that the gun seems to malfunction. |
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Then your buffer/spring isssue should be fine... sometimes folks get the full length stock buffers and springs confused with the shorter colapsible stock ones.... As long as the "chamber" issue is not a problem (shooting 5.56mm ammo in 223 spec chamber) you really should contact DPMS and have them fix your upper. Mike |
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Hey. I have a brand new 20" DPMS upper with the same type of issues. Mine is sort of different though because another bolt/carrier will work in my upper but the bolt/carrier it came with won't. It was one of the chromed carriers. I sent it back to DPMS but they said they can't make it malfunction. I haven't got it back yet but mine seems to be an out of spec bolt issue due to the chroming. I can't imagine I have a lower problem causing these issues. Keep us up to date on what happens and I will do the same. Kevin |
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