When building lightweight rifles is there a general rule for minimum muzzle diameters? I seem to remember someone telling me one time caliber + .250 inches(ie. .625 minimum muzzle diameter for a .375 caliber rifle).

Thanks in advance.

I have no idea what the proper answer to that question is but Cliff LaBounty once told me that some of the original double rifles he's seen through his shop had as little as 80 thousandths wall in the groves (at the muzzle). Not saying this is good in another type of gun, just dredged up an interesting factoid.

Hello Badboyz

I went and measured the muzzle diameter of my 8x68 for you. It was 0.55". Wall thickness 0.113". It's a reasonably energetic cartridge that operates at the 66 000 psi (4 500 B)level. The first time that I fired it was on a very hot summer day - found the primers absolutely flattened and a clear shiny "plateau" at the ejector slot - also the imprint of the butt in burst capilliary vessels on my shoulder muscles.

The pressure at the muzzle is very much lower ~ 650 Bar (9 500 psi)

cheers edi