For those interested, the specified bore diameter is 0.430" at the grooves.
I slugged the barrel of a recently manufactured example and it was right at 0.430"

Thanks.  Mine is still in the box.  Not on purpose...just hasn't made it out yet.

Rob

Thanks brother....

From today:

245 grain Keith style bullet handload



Factory Hornady LEVERevolution 225 gr FTX

Yes! Great stuff man! Thanks! I was wondering about that after picking up a new SBL a few days ago. I had a brain fart and remembered why I never bought a .44 carbine before. Horrible accuracy with that large bore diameter on the old JM Marlins. Still though, that’s not .429”. I wonder why Ruger didn’t bore theirs to .429? I wonder which manufacturers use .430 bullets? Hopefully Winchester because I have my eye on a decently priced half case at a lgs.

I'll shoot for accuracy later on this week. I had to drift the rear sight to the left as my shots were impacting 5" to the right at 50 yards...

I have a original 1894 cowboy 44mag . the cowboy model had cut riffling (ballard) not the marlin microgrove .

not sure of the twist but these have a reputation of being pretty good for accuracy up to 240 gr but not so good with any heavier bullets.

I started out one day to check a bunch of different loads and the first I tried was my heavy pistol load which is 21 gr of 2400 . If i remember this load goes about 1250 fps in a 6" S&W 629 and 1800+ fps in the marlin cowboy. It was quite accurate so I didn't spend any time looking further.

My 1894 Classic has a 1:20" RH twist