My bad, I was looking at the weight of case & primer of 444, 199 grains, usaable grains water is 51.2 on the Marlin case (at least according to Handloaders Digest). I would still question that method of arriving at a max pistol powder charge. The 14 grains sounds ok on a start but I would still limit my max to around 1250-1350 fps, regardless of charge weight. I've never seen data for pistol powder that uses charges of 30 + grains. Regardless that, while the 375 JDJ was developed as a pistol cartrigde, it is in fact a rifle cartridge being fired in a pistol length barrel. I am using a surplus powder, #107, which gibrass lists as a copy of AA #7. It burns just like Blue Dot. In my 45-70, 15 grains drives a 340 grain bullet at 1290 fps. 11 grains of Blue Dot fom my 44 Mag Handi rifle gives me 1270 fps with a 265 grain bullet. The same 11 grains of Blue Dot drives a 200 grain bullet to 1400 fps from my 357 Maximum rifle. I know none of that is 375 JDJ data, but I hope you find it useful in figureing out where you want to go, sorry for my earlier goof.