My Klein's ,Chicago, late '50s Martini Cadet rebore to 357mag
has 12 twist rifling.  Shoots the Lyman 358315 200gr RN over a caseful of 4227 very well. This bullet has a long nose and short body and so does not take up too much space in the case. I have other longer heavier 38 cal bullets I could 
try, but It is very pleasant to shoot with the 200 gr bullet. 
Also, I thought about rechambering to the 357 Max, but "why bother" 
beltfed/arnie