I really enjoyed tinkering with the 44 magnum, and the .45 acp, but currently it's the .357 Sig. I just picked up a P229 SAS Gen II, and even though I haven't started handloading with it, I love it, even with just the factory loads. I've got the dies, brass, primers, and a lb of Power Pistol powder. I'm just waiting on some projectiles. I'm realling looking forward to tweaking a few different loads. I've researched the 357 Sig, and I've got quite a bit of data. It's a very interesting round, a bit limited compared to the 44 magnum, and 45 acp. It's made for speed (velocity), so if you drop the velocity, you mind as well stay with the 9mm, and keep the added capacity.
DBAR