I recently received a trade for a dpms upper and lower chamberd in .450 bushmaster does anybody have a setup like this? I am looking for a big bore AR for hunting and recreation but I don't know that iv ever heard anyone talk about this caliber. Iv Googled it and unless I get into reloading it looks like my only option to get ammo is from the web. I am what some of you could call an AR retard. Don't know much about them.