WB
Yeah TC, Dan Wesson,Marlin,Gary, and lots more
Tuesday, August 27, 2019, 13:28

all use .308" bores for the old traditional .311-.312" caliber cartridges like the .32 H&R, .32-20 etc. It makes things lots easier and when you fire the round it becomes .308" for sure. Works perfectly. I load .309" cast bullets in all my calibers like that including .327 Federal.

The .300 GNR is very close to a .41 Magnum necked to .308" If you really wanted to get technical it is exactly in spec with a .401 Herters necked so! Not that anyone ever thought of that I accidentally found that from forming Herters from .30-30 cases. And YES I had to try one .41 Magnum FL in a .300 GNR die, it don't work, almost but no.

So Gary actually does make your .308-.357 cartridge, he just named it the .321 GNR. The Europeans measure groove to groove and would call that the .320! Gary once re-bored a .30 Carbine cylinder for me to .300 GNR it worked fine.

Only one rare tid-bit; the Ruger .30 Carbine has a strange rate of twist, 1:16.5" I think. It is fine for bullets up to 115 gr. but not beyond. Gary's re-barreled package guns have rifle rates of twist and can handle 60-170 gr. at least. That's what I've shot in .300 GNR. I have one of his .327 Federal barrels in an Encore Pirate. I also have some 230 gr. cast rifle bullets slated to try sub-sonic. We'll see if they hit point on!

This is an actual .401 Herters and a .300 GNR case with custom shorter neck (same case OAL as .30 Carbine). I bet Gary never even realized that. Even the .30 Herrett (1972? Much longer case too) on the .30-30 came after the Herters died.