01-18-2018, 01:08 AM
bj139 Wrote:If a manufacturer follows mil spec for his barrels and bolts doesn't that mean headspace is correct?
I know about the .136" bolt face but didn't Colt establish specs for that so headspace would be correct?
My point is this is not some custom barrel job where headspace can vary depending on what the gunsmith decides..
I'm not remotely an expert so feel free to correct me, but I'm not sure what you mean by "mil spec" because I don't think that term has any real meaning in the context of chamber or bolt dimensions. I take it you are referring to the parts being made within the correct tolerances, for example the barrel being manufactured with a saami spec chamber in such a way that the cartridge will be properly supported at the shoulder and base when used with a true .136" bolt. Opinions obviously vary widely on the necessity of checking head space since it is incredibly rare to have an issue when the barrel and bolt are from established manufacturers.
Nonetheless, barrels and bolts are made by humans using machines with parts subject to wear and misadjustment, so checking head space is nice insurance against the possibility that either the barrel or bolt is out of spec, or both are slightly out of spec such that the errors compound to create a problem. Personally, I'm not exactly religious about checking head space -- I just stuck some layers of masking tape on the back of 2 cartridges to make a poor man's no-go gauge to "check" my newest grendel upper -- but I do think it's prudent to check every barrel/bolt combo whenever possible.