A friend of mine gave me some Lyman 535 grain LRHP cast bullets he got for his 45-70. I would like to try them out in my 450, but can't find any load data for them. Any suggestions on where to find load data for these bullets. The box came with load data for the 45-70 and I thought I might be able to work off this.
What is the general rule for loading cast vice jacketed bullets?. Assuming same bullet weight, would you reduce the powder load on the cast bullets?. By how much?.Any suggestions would be most welcome.

Can I suggest posting this inquiry on the cast forum here at Accurate- or at Shooters.com again per the cast forum. Most likely someone familar with the 450 then might see this question.

I have been using 40 gr of H322 under a 550 gr cast FP GC bullet. Similar to the 540 Garrett bullet. An accurate load in my Guide Gun 45/70 loaded to 2.510" OAL. I use Rem Nickle cases which have less capacity than the brass cases from Win and Rem. Try H322 I think you will like it. BTW this load runs 1490 from 18.5 inches.