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9/22/2017 12:11:25 AM
Posted: 8/17/2003 5:23:48 PM EDT
JUST FINNISHED MY 4TH BUILD . THIS IS FOR A FRIEND. LOWER IS A DPMS. UPPER IS RRA. BARREL AND BOLT ASSY ARE COLT. WOULD IT BE WISE TO HAVE THE HEAD SPACE CHECKED WITH SO MANY DIFFERENT BRAND PARTS
Link Posted: 8/17/2003 6:43:29 PM EDT
My CYA(cover you're a$$) answer would be yes, check your headspace. In reality though, since head space is dependant on the fit of the bolt to the chamber & you are using a Colt barrel & bolt, you should not have to worry.I have put together several home built guns & never had a problem. My latest frankengun uses a used bushmaster barrel & an extremely used G.I. surplus M16 bolt. I used a field gauge to check for excessive head space & it was well within spec.
Link Posted: 8/17/2003 8:33:47 PM EDT
[Last Edit: 8/17/2003 8:36:25 PM EDT by stinkeypete]
You know the right thing to do. You asked the question because you wish you didn't have to do it. If you are building rifles for friends, you have graduated to "pusher-man", you sick bastard! You are just a mouseclick away from building number 5... I know the BRD. I just got a set of gauges from Bushmaster. You want a GO and NO-GO for a new barrel. I did mine, and some might say I wasted my time and $44 bucks. But now you know a little bit about how I build things. Pete
Link Posted: 8/18/2003 2:58:29 PM EDT
thanks guys for all the help . i'm having the head space checked to be on the safe side
Link Posted: 8/19/2003 9:36:29 AM EDT
Weren't you concerned about the headspace in the previous 3 rifles you built? You should have been!
Link Posted: 8/19/2003 1:22:53 PM EDT
Tell me how much the gunsmith charges you to "adjust your headspace". First, The lower receiver has NO EFFECT on headspace. So, take that out of the equation. Secons, the upper receiver has NO EFFECT on headspace. Brand, type, even if it is poorly machined and out of spec, it cannot in any way affect headspace. Take that out of the equation. The barrel and bolt assembly... well, forget about the bolt carrier, that has nothing to do with headspace, either. That leaves us with the only two components that do affect headspace: the barrel and bolt. Both the bolt and barrel are from Colt, not that it makes a bit of difference, and I assume, new. They are, aren't they? Even with "stacked tolerences", the M16/AR15 design is such that new components will assemble and headspace correctly. It does not matter if your bolt and barrel are from DPMS, Colt, RRA, Bushmaster, Armalite, or any of the top makers and parts suppliers. The parts are all supposed to interchange. You can only check headspace properly on the AR15 with gauges made specifically for the M16/AR15 design. And this is always looser than for a .223 bolt gun. This is by design, to allow for easer feeding and extraction by the self-loading action of our favorite rifle. Assemble and go shoot.
Link Posted: 8/19/2003 2:28:17 PM EDT
RUS4777 THE OTHER 3 I BOUGHT THE UPPERS COMPLETE FROM BUSH MASTER ITS A LITTLE MORE COSTLY BUT CUTS OUT A FEW STEPS THX FOR EVERYONES HELP
Link Posted: 8/19/2003 3:20:07 PM EDT
Unless you are installing a barrel extension (and I've never seen anyone actually do that) headspace is a non-issue. Headspace is dependent on the barrel extension (which has the locking lugs) and the bolt (which has the other locking lugs) as well as the chamber depth. You will note that you cannot readily adjust any of these. Any in-spec barrel/extension should properly headspace with any in-spec bolt. I've seen exactly one upper that didn't properly headspace (out of a lot of uppers) and even then it didn't bulge or stretch cases. Not to say headspace isn't an issue. It is. It's just an everyday issue. To be on the safe side, at least get Brownell's Field guage. That way, you will know. With a Field guage and a new, unfired case (not live) you have a pretty good go no-go guage set.
Link Posted: 8/20/2003 7:58:18 AM EDT
What can happen if you fire a gun when the headspace is not right?
Link Posted: 8/22/2003 8:57:14 AM EDT
The brass will stretch slightly, just above the case head. It will show as fine shiny rings around the circumference just above the web. If you continue to use this brass, reloading, you run risk of a case head separation. For an AR15, it would be VERY unlikely you would have this problem with new parts.
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