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Posted: 1/11/2014 5:51:21 PM EDT
I've got a BCM 14.5" upper on the way and a Rainier Arms bcg waiting on it. Do I need to check the headspace before firing? I've been meaning to get some headspace gauges but forgot about it until now 
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If the barrel and bolt was manufactured correctly, and you build it correctly; there should be no need to check headspacing. Just make sure you've got the proper range of torque on the barrel nut and you should be good to go. (30-80 ft.lbs) The upper is already assembled from BCM. |
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The upper is already assembled from BCM. Quoted:
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If the barrel and bolt was manufactured correctly, and you build it correctly; there should be no need to check headspacing. Just make sure you've got the proper range of torque on the barrel nut and you should be good to go. (30-80 ft.lbs) The upper is already assembled from BCM. Oh, I see. My bad. Then just slap the BCG in and take it to the range. Post results. 
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Which upper did you get from BCM, Hammer? 14.5" lightweight middy with pinned A2X 
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Oh, I see. My bad. Then just slap the BCG in and take it to the range. Post results. Quoted:
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If the barrel and bolt was manufactured correctly, and you build it correctly; there should be no need to check headspacing. Just make sure you've got the proper range of torque on the barrel nut and you should be good to go. (30-80 ft.lbs) The upper is already assembled from BCM. Oh, I see. My bad. Then just slap the BCG in and take it to the range. Post results. We'll look at a picture also |
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Right on. What HG you going with this time? |
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Right on. What HG you going with this time? Quoted:
Right on. What HG you going with this time? This one is going to be how my first rifle started. MOE handguards, CTR stock, and a carry handle. That drop in keymod rail from MI looks pretty nice though 
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We'll look at a picture also Quoted:
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If the barrel and bolt was manufactured correctly, and you build it correctly; there should be no need to check headspacing. Just make sure you've got the proper range of torque on the barrel nut and you should be good to go. (30-80 ft.lbs) The upper is already assembled from BCM. Oh, I see. My bad. Then just slap the BCG in and take it to the range. Post results. We'll look at a picture also I don't have the upper yet, it's on the way though. I'll be pic whoring asap once it's here 
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. The only one at my lgs isn't that great and you'll wait 6 weeks to have the sights replaced on a Glock 
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Just buy the headspace gauges and have them on hand for any future build. Gives you ease of mind, especially if you ever buy a BCG from a gunshow.
http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/index.htm?avs%7cCartridge_1=AKK_5xzzx56+mm+NATO |
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I am not sure why there is all this hang wringing over headspace, when there are other barrel/chamber dimensions that can cause all sorts of problems.......which everyone ignores.
Even if headspace checks good, you can blow a case out if the distance from the chamber face to the bolt face is excessive. You can also blow a case out if the approach to the chamber entrance is cut too deep. You guys love to talk about headspace, but ignore the other two issues. If that is the case, you might was well ignore all three. Tony |
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There are all kinds of things that can be wrong, but that does not mean a person should not check what he can.
While it may be a small overall percentage there are never the less periodic posts from people who have a barrel/bolt combination that failed a headspace check. Generally it is the Go gage that fails. |
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What can be done if the bolt closes on the no-go gauge? Depends on the gauge you bought, and your requirements for the gun. If this is a benchrest shooter with a .223 chamber, you return the barrel. If this is a chrome lined blaster, you use a Colt Field II gauge, and see if it closes on that. If it does, you return the barrel for a refund and probably shy away from that manufacturer in the future. If it does not close on the FIELD gauge, then you make a decision, keep is as a shooter understanding it will be a looser chamber than avg, or return it. The chamber spec for .223 SAAMI is from 1.4640 (GO) to 1.4670 (NOGO) This is a "new chamber" range of .003" The chamber spec for 5.56 NATO is from 1.4646 (GO to 1.4706 (NOGO) This is a "new chamber" range of .006" It is possible that you could have a NATO chamber that is considered in spec, but it might close on a SAAMI .223 NOGO gauge, and be perfectly still in spec for a new NATO chamber. Using a COLT II FIELD gauge after closing on your NOGO, you can get a better understanding of "how bad is it". In any case, unless the chamber headspace is longer than the specification for the SAW machinegun (1.50216") it will be safe to fire. The military considers the M16 chamber "no longer serviceable" if it closes on the COLT II FIELD gauge, which is 1.4736" |
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