Quote Originally Posted by John Taylor View Post
When the 375 Winchester came out the reamer companies were selling 38-55 chamber reamers marked 375.. There's only .065" difference in case length. While the 375 may not be as accurate if shot in a 38-55 chamber because of the extra length I think the 38-55 brass will take the pressure. . .
If y'all have a little patience with me, I'm in the process of figuring that out. My Dad just scored an early 2000's Marlin 336 Cowboy in .38-55 that he intends to hunt with this fall, and since he just had shoulder surgery, it's falling to me to shoot his loads over the chrono while he writes stuff down.

We did the initial ladder progression with a custom Accurate gas check mold of (IIRC) about 285 grains, initially using (IIRC) Federal primers deliberately as a canary in the chamber pressure coal mine because he's found them to be thinner/softer/more prone to flatten than the hard CCI military 7.62 spec ones we often use. We were comfortably at over 1600 fps with maybe only the barest sign of puckering the thin primer and still easy extraction when we ran out of test rounds. Going to continue up the ladder from there at a later date. The goal is to hopefully get the trajectory to a point blank on deer to 200 yards. Will definitely NOT be Ballard food!!