Well I finally got to the range. Here is the update. Ruger Bisley Vaquero 357 mag 6in barrel

6.0gr 1076 Average Spread 53 Dev 19
6.2gr 1106 Average Spread 31 Dev 11
6.4gr 1122 Average Spread 80 Dev 28
6.6gr 1138 Average Spread 28 Dev 12

Leading was still pretty bad in the barrel.

I ran across a post that a guy was loading hard cast bullets in 357 magnum. He was having leading with 6.7gr of Unique. He switched to 12.2gr of Accurate #9 and the leading went away. I Had a few bullets left so I had my dad load 20 rounds up with 12.4gr of Accurate #9. BINGO. Very little leading in the barrel.

So I finally learned something. 16-17 Brinell is good for a slow burning powder at Magnum levels but way too hard for 38 special and light magnum loads using a medium burn powder.

And those 12.4gr #9? All 6 shots touching at 10 yards. No I didn't shoot them that good lol, but my dad did. I always let him try my loads for accuracy since he shoots way better than me. That way I know if the load is good and I need more practice, or if the load is just a non accurate load.