Daryl s
I am unable to get Hodgdon Longshot here. There is no comparison on the ADI powder chart. AP 100 has the same burning rate as SR 4756, which I cannot get here either. I cannot find any loading data for this powder. AP 100 is slightly quicker than Hodgdon HS.6. ADI do not list AP 100 in any shotshell loads so you can see why it is taking a while to come up with some comparable loads.
AP70N has the same burning rate as Universal and SR 7625. With 1 1/4 loads 24.9 grains of AP70N is listed at 1300 FPS with 11358 PSI.This is the only loading data reference I have to compare the RB loads and what information you have greatly supplied.

In Wright's book Shooting the English Double Rifle there is a section on the Parodox. One load is 760 grain paradox projectile loaded with 34.5 AP100 with Winch cases and wads for 1100 Fps. Pressure is listed as 3 tons. What does that work out in PSI. I have used this load as a basis for working up some loads. AP70N gives high velocity but is 3.25 tons. It is hard to compare it to modern loading data without knowing the comparison of Tons per square inch and pound per square inch. Can you help. I would like to keep my loads to a maximum of 11.000 PSI.

Another factor when comparing the paradox gun to the Marlin is that the Parodox is smooth bore until the last 4 " or so of barrel where as the Marlin is fully rifled. How will this effect pressure?

As a side note, my daughter who is in Vancouver for 5 months tells me it is a beautiful country. I hope to get there one day.

Bob.
I would be happy with 1300 fps out my 560 grain RB. I have a chronograph on the way to help with load developement. As soon as the results come in I will post them here.
Wayne