AR Sponsor
Posted: 6/23/2008 2:15:43 PM EDT
|
Well I finally got my XM177 upper put together and took it out to the range today. However it would not cycle. I tried it on three different lowers, checked gas rings, gas tube. I'm using a Bushmaster 10 inch heavy barrel that came as an assembled upper half. Any suggestions 
|
Did you put the upper together? I ask because I'm not familiar with Bushamster making 10" barrels, but I'm not an expert. Is the FSB on correctly? Gas tube? Can you post pics? The complete lack of cycling makes me think that there's something preventing the gas from reaching the bolt carrier. |
I never saw a 10" Bushmaster barrel either. Could be a 16" that was cut down without enlarging the gas port. If so, at 10" it would not have enough gas to cycle. Also check to see if the person who assembled it put the gas tube in upside down. He would have had to do some bending to get it to fit, but it has happened before. |
|
FWIW, check to make sure that the gas tube retaining pin is present in the front sight base. If it's missing, the gas tube can move just enough to reduce or completly block the gas flow. I only say this because over the last couple of years I have come across two rifles that were experiencing a failure to cycle and I found they were missing the gas tube retaining pin. |
It's not a cut down 16, maybe 11.5 though, not sure. It is marked under the handguard instead of in front of FSB like other 16 inch Bushmasters i've seen. I did change the barrel from the C7 upper it came assembled with to an A1. I double checked the gas tube, it is installed properly. Also no binding that I can tell. I think it might be getting ready for a trip to ADCO or 45Bravo.
|
|
I found this list while looking for something unrelated to your pronlem. Bolt fails to cycle properly - Make sure screws on clamp type gas block are tight - Make sure gas tube is not binding on bolt - Make sure gas tube retaining pin is in place - Make sure gas tube is not damaged (cracked, bent, etc.) - Check ammo. Cheap factory ammo is often the culprit. Feed it the good stuff during test - There may be a leak around the gas block. This may correct itself with repeated firing due to carbon sealing up the leaks. But check the above first. Check for carbon fouling around FSB |
AR Sponsor