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Posted: 8/2/2012 5:45:11 PM EDT
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All,
I just ordered a Loki 18" Stainless Steel barrel, and now Im looking at Bolt Carrier Groups. I understand that when you get a new barrel and BCG you have to do a head spacing check. What exactly does a head spacing check consist of? Im thinking of the BRO NiB X coated BCG also. Any feedback? Terry |
| Normally when you buy a barrel it comes with its own extension and should be pre head spaced and cif you add in a new bolt and carrier you should not have to headspace it yourself.. I always check them just in case but on the many I have built and helped build I have never had to headspace a new buils,,,now on the other hand if using used components it's a must to check headspace. |
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Headspace is measured from the face of the bolt to a point in the chamber with precision gages.
It is rare to find a combo of new parts out of spec, but it does happen. You should go to the SAAMI web site and read up on this stuff. A quick search will turn up a boat load of info on the internet. |
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Ditto the others. I have done 25 builds and the only time I had NEW issues with headspace was one combination that was a bit too tight and it would not close on a GO gauge (it should, GO means minimum headspace). However, it ran flawlessly and has never missed a beat. If you have any amount of excessive headspace (closes on a FIELD gauge) then the rifle is unsafe to shoot but I have never heard of this happening on a barrel/bolt combination where both were new. In fact, I have not even run across a new B/B combination that would even close on a NO GO gauge which indicates the rifle is at or beyond maximum headspace. IMO if you are going to do the headspace check you need your gauges in this order of purchase if you are not going to buy all three.
If you are only going to buy one gauge, get FIELD. If it closes on a Field you have serious problems. If you are going to buy two gauges, get NO-GO and FIELD. If it ever closes on a NO GO you need to check to see if it will close on a FIELD. If it closes on a NO-GO but not a FIELD, that means you are at maximum headspace and with wear you may get excessive headspace down the road but the rifle is NOT unsafe to shoot if it closes on a NO-GO but not a FIELD. If you get all three, then it should close on a GO (minimum headspace but the rifle is not unsafe to shoot if it will chamber the ammo, which it may not do if the ammo is max and the chamber is minimum), not close on a NO GO but may be safe if it does, and should never close on a FIELD, which is unsafe headspace and may lead to case head separation. Me, I buy all all three just for the hell of it. They are not that expensive but you do need to make sure you know how to use them. You do not just drop them in the chamber and let the bolt slam home. Do your homework first. |
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Hi OP,
As others have mentioned, headspace is nothing more than a measurement representing the dimentions of a chamber in relation to how "well" or tightly a standard (in spec) cartridge will fit into it and the amount of free space between the case head and bolt face. Measuring headspace is done by inserting a gauge into the chamber that contacts a "datum point" (you'll have to research that one to fully understand) (normally referencd to as half way up the cartridge shoulder) and extends back to a point that the bolt face should or should not contact. It is very unlikely that quality new parts are out of spec enough that you must check your headspace. But if you are like most in here (myself included) you won't be comfortable until it is checked. As far as purchasing headspace gauges ... it really depends on the kind of shooting you plan to do and if you reload or if you plan to cut your own chambers ... for the most part, why bother? If you are simply an average shooter and just have a basic plinker/toy or a box or two a year hunting rifle, simply take it to a smith or shop & they will check it for a nominal fee. No hassel. No learning how to do it properly yourself. No taking care of a precision gauge. If you are Captain Rock and Roll himself and burn up cases and cases of mil spec ammo a year, by all means get yourself a "FIELD" gauge and learn how to use it properly. If you build and assemble uppers as a hobby for yourself and friends, and want to perform basic quality control before it goes out the door, purchase a "NO-GO" and learn how to use it properly. The only person that really REALLY needs a "GO" gauge is the guy that plans to cut his own chambers or a smith. How to do it? Read the how to tutorial in the "build it yourself" sticky on Headspacing. Or google it. Do not attempt it until you read up on it. MLG |
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