My OLD Lyman Cast bullet handbook indicates a starting load of 2grains of Red Dot with a CAST 37gr, 41gr, and 45gr cast bullet in the 22 Hornet.
They list a max load of 4gr for the 37gr, 3.8gr for the 41gr and 3.7gr with the 45 grain bullet.
Over the years, I have understood that jacketed bullets do create a bit more pressure then the lead bullets, but I don't know just how much could be expected in this case.
Considering this is a very small centerfire case, and the fact that Lyman Is increasing the load, in the case of the 45gr bullet, by 92.5% to reach the 3.7grain level of Red Dot, it indicates that a little goes a long ways with this powder/case combination.
Personaly, and IN MY HUMBLE OPINION and I could be wrong - again, I think this is a safe load. However, I think I would want to do a bit more checking to make sure.
By the way, the velocities for the three Lyman bullets w/ the 2grain charge of Red Dot are, 37gr - 1210fps, 41gr - 1095fps and 45gr - 1060fps. All fired from a Winchester model 54 w/ 24" barrel - 1-16" twist and .223 groove diameter.
I am using 12gr of RD with jacketed bullets in the 100 - 110 grain range in the wife's 270 and Lyman lists a 12 gr starting load with a 122gr cast bullet. This is a very good reduced load in this situation, easy on the shooter, shoulder, barrel and budget.
Lyman lists a 14gr load as max in the above situation which is just less then a 9.8% increase in this much larger case.
Keep us posted on what you find.
Keep em coming!
CDOC