The Corbon website. Try the link in # 107.
BTW, the .50 mag 400 grain JSP ammo costs $34.95 + shipping for 20 rounds. Including shipping cost, that's over $2 a round. If I had a gun chambered for this round I wouldn't be shooting it much until .50 mag reloading dies go on the market. Then I still wouldn't be shooting it much because my hands and arms would be terminally sore after the 1st 20 shots.
But seriously, with a little judicious experimentation one could devise some nice mild lead bullet handloads that would make the gun into a pussycat for casual recreational shooting. (otherwise known as plinking) Yeah, I know, you can plink with a .22, but I think it would be kinda fun to make .50 caliber holes in Coke cans.