What length of barrel is producing that velocity and dont tell me your ruger redhawks 9.5 inch barrel hits that because I guarentee it doesn't. I know the load you are talking about because it shoots only 1385 fps from a 9.5 test barrel which is still awesome velocity. I dont know where you got 1599fps you are smokin crack dude. And also if you haven't noticed this is a "RELOADING" forum not a factory ammo forum, I will also say no reloader would want to spend 65 dollars a box for 44 mags either, even if they are "Better" then any of our handloads. Because for 65 dollars we could reload , Sh!t thats 1,000 primers a box of 500 cast bullets and a pound of powder. for 65 dollars I can load up 200 rounds of a 44 mag load I guarentee will give that hammerhead load a good run and probably perform better. I shoot this load from a Ruger super redhawk with a 9.5 inch barrel and also shoot it from a marlin 1894 44 mag carbine.

load data:
Bullet: 300 grain hornady XTP/HP, Case: Remington, Primer: Winchester 7 LP, Powder: 19 grains of H110 (Note: Max load) I experienced slight primer flattening. That load had come from Hodgdon powder and the original load data used winchester brass and a Remington 2 1/2 primer
In my redhawk it has a velocity of 1324 fps @ 3 feet and in my marlin carbine it has a velocity of 1473 fps @ 3 feet.