I have no direct knowledge but will offer that what was true many years ago and still true today.
If one went to a recognized master and payed the price, any, of a great many, could and would build a Best gun.
If the contract spells out everything in minute detail and is to the satisfaction of both parties, nothing but good can come of it.
Best,
John

Humble member of the League of Extraodinary Gentlemen (LEG). Joined 14 March, 2006. Member #1.