With 458 bullets running a buck a piece, I thought I would post the load I'm using in my 450 double. Regulates well for my gun. Kills whitetails too.

Hornady cases
500 grain cast bullet gas checked
(rcbs45-500)
78 grains H4831sc
Remington 9 1/2 primers
Hard crimped in top groove

Forgot I use a small piece of 1/2 backer rod over the powder

if you want to go even less expensive and with less recoil, the following has worked well for me in both a bp express rifle and a nitro rifle:

Hornady cases
300 or 325 grain cast gas-checked bullet from GT Bullets
48 grains of IMR4198
Any large rifle primer
1 1/2" long section of 1/2" backer rod over the powder.