Thread: My new toy: a .500 S&W

In my experience which only goes to 45 cal, the old "std" go to for cast bullets of 10 grains of unique has never failed as somewhere to start.
Ive used dacron and other fillers like rolled oats and found they make no difference.
I have also used trailboss in my 45/70 and martini with sucess as well.
There is no reason to get such shotgun patterns with any powder unless the bullet is either not engraving the rifling (microgroove barrels can be bad at this), is to long for the twist rate and is tumbling, or the bore is a different size than the bullet