Asking about cast bullet loading on a forum will produce a lot of "Old Wives' Tales" and plain old misinformation.

I have reloaded cast bullets in my S&W 629, Ruger SBH, Dan Wesson 44H, Contender and Puma carbine starting in '88. I have reloaded everything from cast 123 gr. balls to 300 gr. ingots. Normally I prefer Unique, Universal, 2400 , but I have used, quite successfully, W231 (9.9-11.0) and Bullseye (8.9-9.8 gr) in magnum loads to close to 1,200 fps.

The single most important factor in loading/shooting lead bullets is bullet fit (I didn't see the bullet diameter on the SNS website, measure yours and for starters .431" is a fair starting point). Bullets must be larger than groove diameter to seal the bore and prevent leading, so I size (or purchase) my bullets to the same diameter as the cylinder throats. I have driven my cast (429421 plain base, BHN 12) to well over 1,200 fps many times with no/minimal barrel leading (fit is very important!).

This will get you started, but I recommend getting a copy of Lyman's Cast Bullet Handbook (3rd Edition is a bit better than the 4th, if you can find one) and hanging around the Cast Boolit forum Cast Boolits