Matched Bolts and Barrels

[OldState]

This came up in a discussion about building up a CMP rifle. I see it mentioned by several builder but was wondering if it actually had any real world impact on accuracy. What exactly does it mean?

The concept in question was building a CMP rifle from BCM parts and using their stainless 20" barrel.

[tresmonos]

See post #3:
https://www.m4carbine.net/showthread.php?t=89469&highlight=matched+bolt

A matched bolt is a bolt that head spaced properly.
Max head space guage:
http://www.forsterproducts.com/catalog.asp?prodid=700597

[bp7178]

Some manufactures use different guages, where the actual headspace can be determined, not just go/no-go. Some builders will shoot for a range given the weapons intended use.

If you are spending the money on a premium barrel, and you're going to buy a bolt anyway...

http://www.midwayusa.com/product/549020/forster-complete-match-headspace-gage-set-223-remington