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Posted: 7/24/2009 11:25:20 AM EDT
| I recently built three AR-15's and one of them will not headspace. On the gun that will not head space (go gauge will not go in) I have already changed the barrel because I read that it was the only thing that effects head space. A little about the parts first. I am using a DSA inc. upper receiver with feed ramps and the barrel is a 16 inch 1-7 twist Yankee Hill Machine barrel with M4 extension. Since I have already sent one barrel back and installed the new one I can not believe I would have gotten another bad one (if the first one was bad). Other than the barrel what else could keep the bolt from locking into place? Is it possible for the upper receiver to be out of spec somehow? Like I said the other two rifles which are all identical head spaced with no problem. |
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How close is the bolt to closing?
If it feeds and chamber live ammo that's within spec I'd be tempted to just use it. The barrel/bolt will wear in slightly with use. I usually only worry about excess headspace. I only own FIELD gauges for my rifle calibers and check that yearly. BSW |
| I put everything together and tried live rounds. They would chamber fine and fire but they would not cycle the bolt. It will eject the round and chamber another one if I manually cycle it with the charging handle. Also, I am using an Adams Arms piston kit on it and it is set up the same way the other two were if it maters. Everything with the piston kit seems to be working fine but something is not letting it cycle. Something is keeping the bolt from unlocking. With an empty chamber I can push the piston rod and it will unlock the bolt but not when I fire it. It seems to be getting enough gas to operate the piston. Still very confused. |
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Very odd problem. I read it twice and did not see if you tried different bolts. The reason I ask is that headspace is affected by 2 things: A. Barrel extension B. Bolt I came across one "tight" Wilson barrels with the M4 extension and ended up trying 6 different bolts (mix of RRA and whatever M&A sells) to see which one would close on my Go gauge (same gauge spec as yours). Found 2 out of the six that would close on the go gauge and 4 did not. All 6 would close on a round of live ammo but I'm anal and wanted it to close on a go gauge. I would recommend that you try some different bolts - more than just 2, until you find one that will close on the go gauge. As far as the Adams gas piston kit not cycing the action sorry I can't help you there. |
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