Just a comment about my White inline double in .504 caliber. Using 600 grain slip fit conicals and 120 grains of Pyrodex RS we figured we had similar power to a .375 H&H using the Taylor KO theory. I don't recall the exact figures. The first two shots from the gun are as fast as any gun on the market and with practice I could reload both barrels in 30 seconds using premeasured powder tubes I carried in my vest shell holders, loose bullets in my pocket and a musket cap tool. Not bad but you have to hustle to accomplish this... still even an old Nitro cartridge gun will reload faster which translates to more firepower at your disposal. But for the first two shots, my White is as good as any double of similar size there is. I just think it needs to be bigger for dangerous game and a cartridge gun is a better choice.