Headspaced Bolts

[Jaywalker]

I was just pricing BCM upper groups, and apparently they do not include the bolt, which is a separate purchase with the Bolt Carrier Group. So, I take it, they don't headspace their bolts to the individual barrel/extension.

OTOH, the Grendel barrels generally include a headspaced bolt. Why the difference?

[Variable]

FWIW, there really isn't any user way to adjust headspace. They make bolts to one spec, and the headspace is controlled by the barrel extension. Individually headspaced bolts are highly likely to be a marketing gimmick in the vast majority of cases.

If you buy a barrel and extension that is made to Grendel spec, and you buy a Grendel bolt, then you have components that are theoretically in "spec" with each other. No one (to my knowledge) offers off the shelf bolts that are +.001, +.002, etc. etc.... They just are what they are. If they are both Grendel, and for some reason they don't match, then it is because one was made incorrectly and needs replaced with one that is in spec.

[Jaywalker]

Hmm. Then maybe the inclusion of a bolt with all the barrels I've looked at assumes you're changing from 5.56. That makes sense. Thanks.

[Snew]

I got a "6.5" bolt with a BCG from Palmetto State Armory that won't work so I'm thinking that all bolts out there aren't really "close enough".

[bwaites]

There are at least two versions of "6.5" bolts, one with the face recessed 0.011" inches for the Grendel, and the traditional 7.62x39 bolt. Those two are definitely NOT interchangeable. Unfortunately, some of those who sell 6.5 barrels don't follow the licensed Grendel manufacturers, who all use the recessed bolt. Les Baer also uses the recessed bolt for the .264 LBC, but some of the others chambering in .264 LBC may not.

The only way to be sure is to specify you want a licensed barrel and bolt.