Resurrecting this thread a bit. The past couple of months were spent purchasing a home, closing on said home, then trying to convince the sellers to move out of said home on their contracted date, failing, juggling U-Haul trucks, and finally moving into the home and cleaning up a lot of messes left by the hasty exit the sellers made (only a day or so late, luckily).
BUT let me tell you about how much easier it is to support a casting and reloading hobby when you have a garage and no longer live in a 2-bedroom apartment
On top of that, my wife is thrilled that the reloading equipment and supplies have never even been in the house, and probably never need to, since our garage is well-insulated.
I may or may not have also bought a 3D printer and spent a few weeks playing with that before getting the reloading stuff unpacked.
SO, where we stand now after I read through this whole thread again:
1. I pulled the trigger on a Lee 120gr TC (non-TL) mold. Excited to play with it, but I'll likely have to play with the cavities again, since my M&P seems to like .358" bullets so far.
2. I'm going to try a slightly harder alloy, proceeding with the mindset that 9mm is, in many ways, effectively a rifle cartridge. Probably start with something like 4 parts WW alloy to 1 part foundry type, which boils out to roughly 95/4/1. I was getting plenty good fillout with even less than 1% tin before, and with this alloy my cost per bullet is still well under $0.01, so if it performs, it's a great alloy for the job on all other fronts.
3. I also need to take a measurement of my barrel throat. Presumably this is easier with a short and removable pistol barrel than a rifle. Does anyone have a good way to do a pound cast or otherwise come up with a good measurement? Once I know my throat dimensions, I'll have a really good starting point for target bullet diameter and seating depth.
4. It's probably time I took another whack at knocking the carbide factory crimp ring out of my Lee crimp die. I tried the 9/32 nut driver + hammer approach a couple of years ago and couldn't get it to budge; it's really in there. So since then I've just been skipping the crimp step. My expander die is using a 38 S&W expander plug in place of the stock 9mm Luger one. This is a little wider and a lot longer, so I'm no longer swaging bullets upon seating. My seating die is set up such that it only seats and the crimping part of it never touches the case. I'm at a happy medium where my .358" bullets seat easily and without shaving or swaging, but also don't move after seating even with a lot of thumb pressure, but with a new bullet design I'm not counting on that necessarily remaining the case. At any rate, a crimp step would theoretically help even out inconsistent neck tension since I'm using 100% range pickup brass. I want accuracy, but not enough to sort 9mm headstamps
Will report back after I've had a chance to try some stuff out!