Given: You can fire .38 Special ammunition in a 357 Magnum, but not the reverse.
Many of the "old timey" gun writers, notably a fellow by the name of Skeeter Skelton, who was a Border Patrol Officer, back when they weren't paid much. He was on the pistol team, and could get all the fired .38 Special brass he wanted....free! That's why he used it, but for his Heavy Loads, he recommended and used "expen$ive" 357 Magnum brass. I even loaded up a few of his "Medium" load...13.5 gr. 2400/158 gr. swc...One range session was enough, thank you very much! I was younger then.
I use 357 brass exclusively, but am now trying to load .38 Spl +P level "FBI equivalent" rounds in my 357 revolvers, with velocity from 900-1,000 fps. That's lively enough for me, as I age towards 80. I have heard the old saw;" For 357, take the top load from a .38 special manual., add 5-10%", and FEAR NOT!
My once standard IPSC and everything load was 357 brass, CCI standard Pistol primer, home cast 150gr SWC (RCBS mold) sized .357, 5.5 gr. Unique, chrono'd 860 fps. Nice to shoot, accurate.
In my research, I have found opinions from "shoot 'em like it says in the manual", to "add .01-.03 grain to compensate for the extra space",going from .38 Spl. to Magnum brass.(?)
At present, I have Unique, Universal, Trail Boss and a little 2400, which I won't replace when it is gone. I'm looking for a powder of the same or greater case-filling bulk as Unique and Universal, and I am thinking about Herco, AA#5, HS-6 or maybe Blue dot, using 125-135 gr cast, plated and JHP, 148-150 gr Wadcutters, and 158-165 gr. cast and "J Word" boolits. Low flash would be good. Buy one of each? Not possible on a fixed income, and, at ~ $30 a can, If I buy mistakenly, it will get expen$ive!
O.K., so now, to the questions...
1. I'm not worried about overpressure in my 357, sooo...6gr. Unique being below the start load for .357, that should be a safe and reasonable load for 150-160 gr. lead boolits, do you think? Personal experiences with any of the above powders, or maybe something I haven't considered?
2. I read once that ball powder, as in HS-6, will erode a forcing cone faster than flake....true?
3. If I use Small Pistol Magnum primers, or Winchester SP, which are said to be sufficient for hard-to-ignite powders, too, how will it change the dynamics of the load, if at all? Will a change of primers increase/decrease accuracy or pressures?
Thanks for letting me ramble!