I agree with VarmintGuy. I have probably shot more 38 sp loads in .357 cases in my 686 .357 mag than I have .357 loads.
Years ago when.357 brass was harder to come buy, (more expensive ) I amassed lot of 38 sp from range pickups at bullseye target matches. .The other day I weighed it and I have about 2200 rounds. I don't have a 38 sp handgun except my wife's Lady Smith, but I have three each.357 magnums . Now I have more than that in.357 brass so I have no use for the 38 brass.
I usually load 4.5 grs of Universal Clays or W231, with a 158 gr cast bullet.The Clays, I found to be a lot cleaner burning, but I came upon an 8 pound jug of W231 for free and you can load a LOT of rounds at 4.5 grains with f 8 pounds of powder.
Dittos!
All I shoot out of my 357's are 38 spl loads in 357 brass, the same Universal load saddlesore. Starline brass is plentiful now, stock up.
