Thanks SKB that's a helpful steer, I don't have a copy of that book but feels like something that would be helpful. I had guesstimated a load ivo 90grs and was going to start at 80 - so that data is very helpful. Think I will be lucky to find dies for it though! This is all new to me (double rifles) but have been watching them for some time.
This particular rifle looked too good to miss, which fortunately for me many seemed to; although the proof will be in the pudding as they say. The bullet mould is present so am optimistic.
I saw that gun at auction, looked to be in beautiful condition. The .500 2&1/2" shows up in the Bill Flemming book "British Sporting rifle Cartridges", it shows between 90 and 98 grains of powder and a 340 grain lead bullet.
