If anyone in the USA did this, it would have to be Ernie Stalman of Badger Defense. I am not sure if Ernie is making these, but I do know that some years ago when Holland and Holland reintroduced their Paradox guns, they consulted him and sent him a memento afterwards. It is in Ernie's office.

You could send him an e-mail. There are few nicer people to talk to IMHO.

Good hunting!