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Posted: 2/9/2007 6:35:12 PM EDT
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I chamber a round, fire it and it ejects but seems to only fall out about 2 feet away. It does not chamber the next round. I'm running out of ideas here. I have a 24" bushmaster barrel that came with a bolt, gas tube, and gas block. Here is what I've done to try and fix the problem. Ive used 3 different stocks, 2 different lowers, 5 different mag, 5 different kinds of ammo, 2 different LPKs, and 3 different bolt carriers what should i do next? would a out of spec upper be a problem? One thing i did notice was that the Bushmaster barrel has a dimple for the set screw for the gas block is not 180 degrees from the gas port but the opening diameter on the gas block is still large enough to cover the entire gas port on the barrel even when its canted. |
| Shark, I am no expert, but it would seem that if the gas is not leaking out of the system and the port is of sufficient size to allow enough gas pressure, then the ammunition could be the issue. However, if the ammunition is full spec, then the movement of the bolt/carrier/key group should be checked for freedom of movement. It does sound that your suspicions about the gas block should be investigated first though. If it is not properly aligned TDC then perhaps the key is not engaging the gas tube properly. Do a visual on the stripped upper in the inverted position. Make sure the carrier is smoothly doing it's thing. It would be a small matter to re-align the dimple for proper installation of the gas block. Just based upon the number of different parts combinations you have tried, I would think your problem lies in the barrel assembly somehow. Good luck and pray for the savior (Dano) to help you! |
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I did straiten out the gas block and its perfectly center over the port on the barrel. The bolt and carrier is one of the smoothest out of all my rifles. The first thing im going to do tomorrow is put a Troy gas block on it. I have a few spare around and a new gas tube and see if that does anything. Then I am thinking i should call bushmaster and see what they say. But im still open for suggestions and maybe i can get this running this weekend. if this helps this is the barrel i have Bushmaster 24in Varminter |
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Ammo type being used? Is the chamber 223 or 5.56 Nato? When you pulled the gas block, did you confirm that the Block gas passage and the gas tube opening are aligned? Solvent being used to clean and lube the rifle? Visual condition of the chamber side walls (smooth or reamer grooved), and did the bolt/barrel head space correctly? Hammer wedging (marks behind the hook on the disco/on the top back of the trigger)? B/C passes the 45* tilt test? |
It got fixed last night. A gunsmith friend of mine see this before and opened the gas port a little. We tested it out and it worked perfect. ETA: Thanks for everyone's help this has to be now the best running AR I own |
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Shark15, On the Hoppes, it's fine to use it to clean the chamber and bore, but make sure to remove all of the solvent after cleaning. As for the rest of the rifle in regards to cleaning and lubing, switch over to CLP for that. As for increasing port size, it may have needed it if it was drilled undersize to start with, or you may just have had a rough plated chamber that will self polish out through live fire. In a few thousands rounds, note if the recoil of the rifle seems to be excessive. If it does, then you will need to add some more weight to the carrier to slow the stroke back down from the barrel being over ported. |
By just shining a flash light into the chamber it looks alright but what would be the best way for inspecting its smoothness? Is it too soon to use a heavy carrier or should I wait until a noticeable increase in recoil? Could you suggest a brand of CLP? Would Rem Oil be good or should i get something else? How about the bore, is there something betting i should be cleaning it with? |
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Wait on adding the buffer or carrier mass, you may not need it if the port was too small to begin with. As stated, if the chamber was rough to begin with, it will polish out in a thousand rounds or so and the recoil may become excessive. Note: Don’t confuse a weak recoil spring with an over sized port. If say in 6K of rounds, you start getting excessive recoil, it’s a spring problem, and not the port/chamber condition problem that would have revealed it’s self within a few thousand rounds since the barrel was new. As for bore solvent, Sweets works faster without needing to do heavy scrubbing, but the chamber should still be scrubbed with a chamber brush each time. Also note, Sweets does not leave a protective coating, so plan on leaving a protective coating in the bore between shootings/ for storage. CLP will work for this, but since CLP does have Teflon, even after dry patching the CLP out of the bore to get it ready for a shooting session, a thin Teflon coating is left behind, and will take about 15 rounds of live fire to clear it out of the bore (read will have increased group sizes until the Teflon is shoot out of the bore). As for CLP, BreakfreeCLP in the 16 oz. spray can goes for less than $10 at Wal-Mart (automotive section) or any of the standard sporting good stores. |
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