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1/25/2018 7:38:29 AM
Posted: 12/19/2001 11:29:53 AM EST
i know, i know. "they" say not to. but, i'm wondering exactly how important it is not to switch bolts. i'm looking to purchase an m4 style upper. unfortunately, i do not have the money to purchase one with the bolt and carrier. i have an upper right now with less than 500 rounds through it. considering the relative newness of my current bolt, would i have to worry that much? i would, of course, get the headspace checked by a competent gunsmith.
Link Posted: 12/19/2001 1:37:22 PM EST
How important is it to you if your rifle goes ka-BOOM?

Headspace on ARs is set by the bolt and the barrel. Both have their own range of tolerances. When manufacturers sell complete uppers, they check the headspace and replace bolts/barrels until it's perfect. The odds are your used bolt will fit a new upper are pretty good, but far from a sure thing. If they are from different manufacturers or even different manufacturing runs by the same company, the odds increase that headspace won't be correct.

If your gunsmith checks and the headspace is too large, unless he has a good inventory of bolts and is willing to go through them and test each until it fits your upper, you'll probably have to send the new upper back to the manufacturer for fitting of a new bolt. More expensive and time-consuming.

Now, all that really counts here is the bolt itself -- the carrier assembly has no effect on headspace. A stripped bolt doesn't cost THAT much, and as long as you keep the right bolt with the correct gun, you can swap your carrier back and forth at will.

Link Posted: 12/19/2001 1:48:59 PM EST
thanks for the reply. yeah, i realized after i posted that just getting a new stripped bolt would work.
Link Posted: 12/19/2001 2:58:38 PM EST
Actually the head space is set with the installaton of the barrel extension.

When I was in the Army we would assembly line clean our rifles. I took all the bolts from 5 different rifles and took them down the latrine and dis-assembled them and washed them in a sink with hot soapy water.

Hell most bolts didn't even get their right parts back let alone get back into the right rifle. Never heard of a kaboom.

A prudent person would check any new or replacement bolt with some chamber gages though. They run about $15.00.
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