I recently put together a .22LR AR-15 upper and I'm having a ball with that thing! 
So, not to be outdone, my friend is getting a .450 Bushmaster upper.
Ammo for that thing is like $2 a pop!
Even the individual bullets are ridiculously priced IMO.
He's wealthy, I'm not.
So I immediately started wondering if you could put together a reload using maybe a .45 ACP or .45 Colt bullet and some type handgun powder.
I think he said the bore is .452 so maybe a cast and copper coated .45 ACP bullet would fit?
It doesn't have to cycle the action, and I'm just wondering if anything like that has been done before?

So, not to be outdone, my friend is getting a .450 Bushmaster upper.

Ammo for that thing is like $2 a pop!

Even the individual bullets are ridiculously priced IMO.
He's wealthy, I'm not.

So I immediately started wondering if you could put together a reload using maybe a .45 ACP or .45 Colt bullet and some type handgun powder.
I think he said the bore is .452 so maybe a cast and copper coated .45 ACP bullet would fit?
It doesn't have to cycle the action, and I'm just wondering if anything like that has been done before?