Congratulations on a good gun at a good price
My 6 1/2" also came from Buds
50AE and 500 S&W Magnum are not interchangeable cartridges.
500 S&W ammunition is just going to be pricey. Never use
inexpensive and
500 S&W Magnum in the same sentence
.
Even hand-loads are up there due to projectile cost.
Just go slow to start and if cost is truly a primary concern then hand-loading is the way to go.
NONE of my firearms chambered for 500 S&W Magnum have ever shot a factory load, but I was hand-loading decades before the 500 S&W cartridge came on the market.
I was actually shooting the 500 S&W cartridge the summer before S&W introduced the revolver. Factory ammunition and loading data did not yet exist.
Many of us also cast. These days I have half a dozen custom molds for the my 500 firearms.