Ruger Super Blackhawk

I have been playing with loads for my 44 subgunfan has helped me out some. The problem I ran into was severe leading with .429 255gr SWC correct me if I am wrong SGF. Well I checked my cylinders and for some reason someone has opened them up or something to .431 to .432 supposed to have been a new gun from a Ruger rep wrong I got it home and had to clean the suit off of it. .429's fell through it. I was told not to try bigger bullets but everything I have researched has told me to do so. My first loads were 240gr SWC .432 from Dardas great bullets by the way over 20gr. of 2400 . No signs of leading and at 40yds put all six in a small bull touching each other. Could anyone guess at velocity all I want is a good deer sized load out to 50yds right now I just want it to be adequate (plenty of knock down) humanely dispatch deer.