Thank you doubleD and georgegibbs505.

The action was orginally a Greener shotgun and now it has a sporting stock which is much better than the Martini Henry. I will go check the Lyman book, although the 45-120 is a bit bigger than 45-100. I will work up loads starting with some of my nitro loads that I have used in the rolling block 45.70 with a 28" barrel which gave 2350 fps with a 300 grain at 27,000psi.

Wayne