14.5 is 2x the energy of 50 BMG.
Their powder is a very special slow powder similar to the artillery small bore: 20, 25 or 30 mil, but I believe that US869 would do with a 50 cal primer.
To get unprimed brass into the country I need at least an order of 10,000 pieces, for which I have no funds. Greentips was weary of a group deal as he was not convinced it was legal, so this is still not happening.
Do you know of a source for PTRS? I never saw it for sale. And actually it's not that much fun to shoot as PTRD from what I was told due to enormous unbuffered recoil.