I can't help you with the specifics you're requesting because I don't have a 357 Maximum. However, the fact that you are getting good groups with a 200 grain bullet and not doing well with a 160 grain wadcutter may provide a clue as to why. Current thoughts on Twist Rates is that the longer the bullet the faster you have to spin it to keep it stabilized. For the weight Wadcutter profile bullets tend to pack the mass of the bullet into the shortest possible package. I think your issue isn't the lead bullet, it's the profile. You simply have a twist rate in your barrel that isn't well suited to the length of your bullet.
Another factor in play may be that you are going subsonic because Wadcutters aren't very aerodynamic. In fact they are about the least aerodynamic bullet you can find. So, what may start out at 1500 fps may only be clocking 950 fps 100 yards out. Spend some time around some long range precision rifle shooters and you'll hear lots of discussion about the supersonic range of various calibers, loads, and bullet weights. Because any time a bullet transitions through the sound barrier you get a real and observable loss in accuracy.
So, what to do. First, consider that particular bullet mold a good choice for plinking loads in 357 Magnum or 38 special and keep the bullets Subsonic. Second, start shopping for a mold that produces a longer round, or pointy nosed, profile. Third, if it means going heavier to gain length don't be afraid to do it. Yeah, it may mean having a custom mold made but you should be used to that by now, the 357 Maximum isn't exactly common.
Finally, stop messing around with all those fast burning powders, with your case volume that is an invitation to a blown up gun. I would suggest that you shop for some H110/W296, N110, N120, 4227, or 2400. I've found the key for good velocity with a heavier bullet in 357 Magnum is a good slow burning powder, not something on the fast end of the scale.
