I've shot mine with as much as 150g of Goex 2f and a patched round ball, and it isn't uncomfortable IMHO. I thought about using conicals as well, but I can't think of a reliable way of keeping the left barrel load in place during recoil. I checked the RB load several times after firing one barrel and it has never moved. These guns seem quite stout to me, though I don't know what they are proofed at. Certainly 150g under a conical is a lot more pressure than my load. I'd love to get it up to 200g but haven't had the time to work up to that gradually. At 150 g the gun showed no signs whatsoever of high pressure (hammer blown back to half cock, cap fragments blown off, patches cut) and the patches looked great. That's a lot of whack downrange, btw!
Richard