This group was shot as fast as I could reload the rifle.
I did not keep photos of all my ladders, most were not worthy of consideration, but happy to share load data if interested. I tested two different bullets and 2 different powders. I got the best accuracy with the 38sp loads so far. I did not have much luck with cast bullets in 357 yet. Groups were as wide as 8 inches at 30 yards. Not good.
My plan is to pick up some jacketed bullets for my 357 loads, something that expands, worthy of taking down larger game. And I have a nice accurate 38sp load for the small game using my cast projectiles.
One thing I did notice however is that the rifle has a small chamber. Typical jacketed bullets will size at .357 inches. I would normally cast and size bullets to .358 inches. When inserting loaded rounds into the M6 that were sized to .358, I noticed that they need to be pushed into the chamber, and were difficult to remove if not fired. When sized to .357, the rounds drop in and out without any fuss. In order to get reliable chambering, I had to size all of my cast down to .357. I think that the poor accuracy with the magnum loads has to do with the cast bullets being slightly undersized for the bore. This is why I plan to use a jacketed bullet for the hot loads.
Cheers.