I have the bore guide like your picture and I got mine from Brownell’s. My bore guide works good and was inexpensive. I don’t remember how it was listed for use with different calibers. I use this bore guide with a Dewey rod.
https://www.brownells.com/gun-cleaning-c...d5632.aspx
If I were buying today I’d buy the bore guide for the 6.8 SPC (.277) which would work with 6.5/.264.
https://www.brownells.com/gun-cleaning-c...d5632.aspx
If I were buying today I’d buy the bore guide for the 6.8 SPC (.277) which would work with 6.5/.264.

