Posted: 12/7/2011 7:26:28 AM EDT
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Someone in another thread brought this up but I don't understand...
It's impossible for a homebuilder to improperly headspace an AR isn't it? There are no possible adjustments to make when placing the barrel onto the upper receiver... At least that's how it was when I made mine. Unless you make the upper receiver and barrel from a block of metal, the headspace is already set when you buy your parts So how do you change the headspace in an AR? P.S. Mine had light strike issues so I tested the hammer and noticed it felt weak so I took it apart and found out I put the hammer spring in backwards  I fixed it... 0 problems since!
That never would have happened if a professional had made the gun! |
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So how do you change the headspace in an AR? To go tighter, assuming you already have a new bolt: Replace the barrel extension To go looser, you can lap the back surfaces of the bolt lugs. All AR barrels that you will buy have a pre-installed barrel extension set within headspace. If you use a new bolt with a new barrel, you're GTG. Even from different manufacturers, you're fine as long as all parts are built to spec. If you ever need to replace a bolt before you replace the barrel, you should re-check the headspace to make sure you're still OK. |
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Don't have to, in the sense that it's PROBABLY ok. On the other hand, you're trusting that the barrel extension is correct AND the bolt is correct. I imagine the specs are setup so that even if they're at opposite ends of the tolerances it's still ok, but...
Personally, I'd rather just check it real fast. I don't personally have a set of gauges for 5.56 but the shop that pinned my comp for me does and they were nice enough to do it for me. You're talking about thirty seconds total if nothing's wrong. |
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It's impossible for a homebuilder to improperly headspace an AR isn't it? I am not a professional but that is my understanding as well. So long as the manufacturer of the barrel, upper receiver and bolt carrier group have done their jobs correctly, headspace should be fine. I have encountered ONE headspace problem in my time as an AR enthusiast –– with a brand new LMT upper.  It would not close on a "go" headspace gauge, even with four different brands of BCGs (BCM, Bushmaster, Armalite and RRA). I sent it back to LMT in August and it's still there. I guess even the "professionals" can screw things up now and again.
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AR's are a lot less prone to headspace issues unlike the M1 and M14 rifles. AR bolts are much more uniform. That is not to say you can't have headspace issues, but usually they are due to out of spec parts or a rifle that was not chambered properly to begin with.
On the M1 and M14, switching bolts can get you in a lot of trouble. |
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AR's are a lot less prone to headspace issues unlike the M1 and M14 rifles. AR bolts are much more uniform. That is not to say you can't have headspace issues, but usually they are due to out of spec parts or a rifle that was not chambered properly to begin with. On the M1 and M14, switching bolts can get you in a lot of trouble. Yeah, don't play mix-and-match with Garands unless you have a set of gauges. Bad ju-ju right there. |
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AR's are a lot less prone to headspace issues unlike the M1 and M14 rifles. AR bolts are much more uniform. That is not to say you can't have headspace issues, but usually they are due to out of spec parts or a rifle that was not chambered properly to begin with. On the M1 and M14, switching bolts can get you in a lot of trouble. Yeah, don't play mix-and-match with Garands unless you have a set of gauges. Bad ju-ju right there. Not only the gauges but a bucket full of bolts! |
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You're trusting the manufacturers to have built the bolt to within specs and to have set the barrel extension within specs if you assemble a rifle and don't check the headspace. Do you check the headspace on every NEW AR you buy? I mean, manufacturers and small shops would never get the headspace wrong since they are professionals right? Oh wait... A previous poster in this thread got a NEW LMT upper that was headspaced wrong... |
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You're trusting the manufacturers to have built the bolt to within specs and to have set the barrel extension within specs if you assemble a rifle and don't check the headspace. Do you check the headspace on every NEW AR you buy? I mean, manufacturers and small shops would never get the headspace wrong since they are professionals right? Oh wait... A previous poster in this thread got a NEW LMT upper that was headspaced wrong... Apparently, manufacturers will check headspace on rifles they assemble before they leave the factory. But ones you assemble yourself don't get that headspace check unless you do it. I went ahead and spent the extra $50 for a set of headspace gauges for my first build. I considered it part of the expense for the tools. Of course, it checked out perfectly.  And at least I got a set of headspace gauges now too, so I CAN check all new ARs I buy, I ever buy complete again.
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