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Posted: 9/1/2009 3:35:17 PM EDT
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stock bushmaster A2 lower with rifle length buffer and spring. works fine with my LMT 16" upper but when i put on an upper with a 24" bull barrel i get a jam every 6th or 7th round. Should i try a carbine buffer and/or spring?
Thanks. |
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need more info. What type of jam?
The first thing I'd check is the gas system. Did you try using the BGG from the 16" upper? That will eliminate the question of gas keys. gas rings from the equation. If you did and it didn't help, then check the gas tube for kinks and check the gas block/FSB for gas leaks. You have a rifle length upper, so I think the rifle buffer will be fine, especially since the 16" upper works fine with it. |
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DPMS 24" bull barrel with low profile block ove a free floating hand guard. no kinks in the tube.
yankee hill reciever with bravo company BCG. it ejects the fired round but jams on picking up the next round. using 20rd P-mags. How would i check for a gas leak at the block? |
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To check for a gas leak, look for carbon fouling at the gas block. if you see a lot, there is a leak. A small amount is normal on a brand new rifle, but should seal up after a hundred rounds or so.
Double check that the gas block is lined up properly over the port in the barrel, if it is canted slightly or partially blocking the hole it will cause the same issue as a leak, too. The symptoms you are describing are classic gas problem issues. If your tube isn't kinked, its either one end or the other (bolt carrier keys, gas ring alignment or gas block alignment) |
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Quoted:
stock bushmaster A2 lower with rifle length buffer and spring. works fine with my LMT 16" upper but when i put on an upper with a 24" bull barrel i get a jam every 6th or 7th round. Should i try a carbine buffer and/or spring? Thanks. Hell NO!!!!!!!! The receiver extension tube inner void dictates the length of the spring and buffer needed. You drop in a Carbine buffer into a full length tube and the end result is going to be a cracked lower receiver, since instead of the buffer limiting out the reward movement of the carrier key before it reaches the back of the receiver, the carbine buffer is going to allow the back of the key to crash into the back of the receiver full strength (read at the top of the tube threaded section, cracking it off the rest of the receiver). |
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Quoted:
If the bolt is trying to pickup the next round, I don't think it's a gas issue. Have you used a different mag? How does the upper and lower match up inside the magwell, especially the front transition? Also take a look at the upper receiver just below the feed ramps for signs of low bullet feeding (dents just below the barrel extension lugs). |
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