Posted: 7/18/2012 12:56:05 PM EDT
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I got my first ar a couple months ago(RRA varmint) I guess I've been bitten as I'm working on my second one now. I've got a sog arms lower and a Vltor upper receiver,trying to decide whether to build on that or buy an upper. What determines the head space, the bolt and barrel or the receiver and barrel? Being pretty new to this I'm kind of leaning toward selling the Vltor upper receiver and just buying an upper. I have a bcg. any help appreciated
Thanks Mike |
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IIRC the poor mans way to check headspace was get a factory spec round and place a single piece of cellophane tape on the base, the bolt should close and lock. Place a second piece and it should not close/lock.
However it has been many years so I might have this wrong. And like mentioned above, the barrel/barrel extension is what determines headspace unless somehow you got a really wonked out bolt. |
| As noted above the headspace is set when the bolt and barrel extension are machined. The only way to adjust it is to swap bolts, but that isn't necessary unless you have an out of spec part. I have seen 2 out of spec bolts that caused issues (one mine, one was brought to me). I don't think it happens very often but it's a PITA when the bolt jams up just prior to being fully closed on a live round. You can't open the receiver at that point. I'm pretty sure this could be diagnosed by opening the receiver and closing the bolt by hand on an empty round prior to heading to the range. |