First off I dont know about jacket thickness, heat treating and all that. I spent a lot of time working up loads in a Cooper rifle. I tried all the powders you listed and then some. There wasnt much difference at all. Overall and using Berger 30, 35 and 40 gr., Sierra 32 and 39 and Hornady 32, and 40 gr. bullets, I got the highest velocity and best groups using either H-335 or Win 748. The bullets I settled on were the 32 gr. Sierra and both the 35 gr. And 40 gr. Berger. The 40 gr. Berger will flat smack, at least on diggers. Its the only bullet I tested that is a hollow point and a boat tail. It is holding up good out to 400 yards and I havent shot farther. At least that I know of
! As a side note, no matter what I tried I could not find a combination of loading to make the 32 grain V-Max shoot. As far as group size they were the worst and that was a surprise to me. Another thing I learned with my 204, the faster they go the better they group almost without exception. Bench rest primers turned out to be a must also.
