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Posted: 4/27/2008 7:28:47 PM EDT
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If I buy an upper without the bolt/carrier group - Can I use any bolt out of another upper without having a headspace problem? Or would I have to buy a seperate bolt and have it headspaced to the new upper? Thanks Emerson |
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Always keep the bolt with the barrel. Getting a new bolt for a used barrel is never a problem, but putting a old bolt in a new (or used) barrel MAY cause excessive headspace. Swapping a bolt between barrel will certainly increase wear on the bolt lugs. In any event if you put a used bolt in any barrel you should test the headspace with a Field Gauge (preferably the USGI one). Moving a BOLT CARRIER between uppers is never a problem, but the bolt itself can be. |
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There's something I don't get... when you drop the field gauge in the chamber of your 5.56 NATO and attempt to close the bolt with finger pressure (according to the TM manual), it should not close and the carrier should extend past the end of the receiver. If you were to drop that field gauge into a .223 chamber (which should be tighter), you'd get the same result, correct? Logically, you should not be able to close the bolt and the carrier should extend past the receiver a slight bit more than in a 5.56. When changing a barrel or bolt, the field gauge only tells you half the story, but it should be ok if you KNOW your barrel is 5.56. The field gauge is ONLY accurate in a 5.56. Do not use the field gauge (the military one) in a .223. Am I making sense? |
That is correct.
The 5.56 field gauges allows for a bit more stretch than the .223 and it should not be a problem (if the rifle isn't a precision rig). As for only telling 'half' the story. Having a chamber that is too short should not be a problem if you buy quality barrels. Buying cheap unknown tubes from a gun show vendor and all bets are off. However, if you can chamber a round w/o an issue you should have the 'too short' base covered. 
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