That's an idea that has crossed my mind Jim but I've always imagined taking my Boyes to some indoor .22 RF range, slide in a conveyor and watch the faces of the shooters around me as they scramble for their hearing protection and the RO only to have a virtually indistinguishable "pop" come from the barrel. The .50 AE might work in a .50 BMG conveyor if you can find some of the original ammo in .510" but the new stuff along with the .50 S&W are now a true .500". There wouldn't be a huge cost saving either with the handgun cartridges which run aound $1.50/round. I made a bulk purchase of surplus .50 BMG ammo for $2.49/ round a few years back.
Regards, Derek