I still have it, and shoot primarily cast in it. Since I powder coat my bullets I've taken to water dropping them straight out of the PC oven. I haven't attempted to check the hardness, but I'm satisfied with the performance of my bullets for both the SIG and 9mm when done this way. My primary 9mm bullet has been an NOE 357-135-RF, I believe this is a Ranch Dog design. It has worked well in both calibers, at least until my new M&P 9mm Compact came along. It does not appreciate the big meplat of this design at all. I have other bullet designs that should work for it, and the bottleneck 357 SIG cases feed really well with it.
I am loading my 357 cases at full power using data for 140 gr jacketed bullets since my 135 gr cast are actually right around 142-143 gr, ready to load. There is also some really limited loading data for 147 Lyman cast in 357, and I'll get around to working up data for 358156 in it as well. It loaded without the gascheck the 358156 has a profile similar to the afore mentioned Lyman 147 gr cast design and feeds perfectly in every 9mm I've tried it in so far. You are on your own as far as loading data goes however, but in the 357 SIG you should be able to develop some loading data for it even with a gascheck. I leave gaschecks off for 9mm because of the inner case taper.
I now have 4 cavity Lyman moulds for 356637 (147 gr) and 356402 (120 gr) that I have yet to cast with too, so there's plenty to work with. One favorite powder for me has been IMR (now Hodgdon) 800X, AA#7, Unique, and I have a couple of pounds of WSF that should do nicely as well. I really like the caliber and feel it has been dismissed too quickly as being only slightly better than 9mm +P. My experiences lead me to believe that the velocity difference can be quite an advantage with the correct bullets. I have also found that bullet manufacturers seem to publish reloading data for 357 SIG that throttles it back to work with their optimal performance envelope for 9mm bullet design, Hornady seems to be the worst offender here.
With bullets like Speers 125 gr "Gold Dot" bullet, specifically designed for the SIG, or even proper hard cast bullets the SIG is capable of higher performance than it has been given credit for. Another experiment I have planned is to try swaging down 125 & 140 gr jacketed 357 magnum bullets to .356-.357 and testing them. FWIW, Speer 125 gr SIG bullet appears to be the same bullet as their 357 mag. bullet, but without a cannelure. It is not even close to their 124 gr 9mm design.