I just picked one up, and test fired last week. I used some of my 38/55 loads, both lead(1250fps) and jacketed(1680fps). Both shot well, but the Hornaday jacketed is more accurate, the cast needs to be tuned to the micro groove a bit better.
I used new 38/55 brass that measures exactly the same as the 375 spec. Left it longer(2.085) than the trim to length(2.015) and had no chambering issues. Starline makes two lengths, so get the shorter for use in the 375. I had no problems in the neck diameter area. I think I'll shoot for a 1900 to 1950 fps load and see what the groups look like.
