A friend wants to start reloading the 50 AE
is this a .500 dia. bullet?....what is the powder of choice?...H-110?
Can one fire cast bullets in this thing?
any help will be appreciated.

I'm guessing that he's shooting them out of a dessert eagle don't use cast bullets in gas
operated semi autos also your choice of 50 cal
bullets are limited because of the lengh

Yes it is a .500 cal bullet. And as claudeb pointed out if it's a Desert Eagle you don't want to shoot lead bullets in them because it is gas operated. Bullet selection is pretty much limited to Speer 300gr and 325grainers unless you load the cheaper plated ones from Berry or Ranier. I've shot them all in mine without any problems.