Back to basics. Determine throat diameter and size to .001 under or less. Ignore groove diameter. That alloy is way harder than you need for those velocities too.
I don't know if you do much shopping for 38-55 bullets, but there isn't a whole lot of them on the market. I don't cast. Newer 38-55 have .376 diameter. which says the .375, or .376 should work in a newer barrel but older ,38-55 barrels vary on the.379- .380 diameter and most likely their throats vary too.
I am trying to come up with a match for this 1906 Winchester without spending $600 or so for a reline or new barrel.
These bullets I have are marked Ballard.I guess there may be different specs when the Ballards came out, but all the brass is the same
