Quote Originally Posted by foxtrot
Zero chance, sorry buddy. Even the lightest bmg rounds would over pressure a 50 s&w case, if they would fit (they wont). BMG rounds would either occupy too much of the case causing pressure problems, or far exceed max col (length) of the cartridge, contacting the rifling and causing a serious saftey issue.

Dont attempt it even if it looks like it will work. Someone will have to scrape your arm off the benchrest at the range.
+1 even if you could somehow load it, it would be to long to even close the cylinder.