The only one that I know of, is Rob Furlongs actual rifle, and it was on display here at the Museum of the Regiments (?) on Crowchild Trail. They may be able to help you find one, or lend you one of theirs.
You fella's probably know this already, but it is the US that prohibits the export of any US made .50 cal rilfe. So, other than a military application, they would be very difficult to find. Hope this helps.
R.