Mine is actually a "300 Fireball". It's a "Frankenrifle" with a Model 1 Sales barrel, DPMS upper, Essential arms Lower, and a milspec bolt group. I assembled it myself. I would catch a part I needed on sale and purchase it, put it in the dresser drawer, until I got everything I needed.
Given the performance range of that cartridge, I don't think you would have to worry about special cast bullet loads.
I hadn't thought of that, you're probably right. It is a very versatile cartridge.
I've shot both subsonic and supersonic loads through it with no problems.