...Welcome aboard. Whataya wanna do with the ammo? Light target or awesome SD loads? Kinda sounds like you're into SD loads. I'm playin' with 140 gr Speer 357 Mag bullets resized to 0.355" and 0.356" with great results. But some of the most pleasant loads involve 88-95 gr .380 Auto bullets (0.356"). Lazer trajectory with minimum recoil. Still, the 124-125 gr JHP's are the easiest to deal with, consistancy-wise. The Remington 125 gr JHP's are a good choice without goin' too "exotic". This cartridge has true diversity and I've had great results with reloads using 88-140 gr's bullets from 1200-1600+ fps. I've tried some 158 gr 357 Mag bullets resized to 0.356" and 0.355", but that's just too much bullet for a semiauto 357 SIG with a 4" barrel. <shrug> Powder-wise, Power Pistol is my favorite but has quite a flash. I've found that Herco and Vihtavuori N340 are great for target loads...very pleasant and consistant. Bullseye is always a blast and the only powder I've approched higher end performance barriers with. Whatever the challenge, my M357-A1 chews through everything I've fed it like a champ. I've read posts involving FTE prob's with M9's and M40's. SAI is aware of it and a permanent fix is in the works. The only time I've experienced FTE's with my 357-A1 is with Bullseye and pushing the end of the performance envelope for the 357 SIG cartridge...and always using 0.357" dia bullets. When org's like TX Rangers, Special Forces, and CIA are switchin' over, well...must be for some good reasons, IMHO.
Its only a matter of time til machine pistols chambered for the 357 SIG hit the market...a flatter trajectory bullet with a light recoil, more feeding reliability and greater performance makes for a superior conduit for small arms self defense scenarios, IMHO. Anyway, PM me if you like for specific reload recipes. Hava great Labor Day weekend.