I dragged this thread back into the present, because of stumbling across an image in "Ed McGivern's Book" (that's actually its name; the 'fast and fancy' portion is a subtitle).
From it I would expect that the holster on the NM deputy is an A.H. Hardy. Dates even work; the book is (c) 1938, the deputy pic is 1940. The styling and construction around the stitched welt is unmistakeably identical in my view.
Hardy, best known for being a trick shooter as was Ed, and for a shoulder holster that Cooper had Milt Sparks copy (which was just like every other maker's "C" clip spring holster)(Cooper added a slit near the muzzle for the waistbelt which actually was a good idea) was from NE but made holsters after a shift to Denver (can't be a coincidence that Heiser was in Denver) by 1920, then on to Beverly Hills by 1930 which is where Cooper encountered him immediately after the War. Hardy holsters with each of the two cities, and with no city, have been recorded. Hardy died the year I was born, 1950.
I got McGivern's book recently, because I had not ever looked through it and when locating an image from it on the Web, realised that he wasn't just a tricker shooter using a handheld pistol; he was a trick shooter from the holster. Course y'all knew that but I didn't. Heavy on the Myres products with a nod to Berns-Martin.
His notion, that a real gunman will have a holstermaker fit him up special, matches up with very similar language in the Sykes-Fairbairn book of the same era; which also mentions B-M in general and Jack Martin in particular. Several references including Fleming's man Boothroyd associate Martin 'the man' without mentioning John Berns (it is clear that he was the inventor and it was Martin who 'reduced the invention to practice' as the USPTO calls the process; and made all the unmarked, and the Calhoun City holsters; the Elberton holsters were made by another).
Today I don't think it would be good advice to advise a 'serious gunman' that he had to visit a holster maker to have his holster designed and made just for him; unless he wanted to carry it someplace out of the ordinary (Paris' crotch holster comes to mind) or had a disability. Likely his tailor, instead, to perfectly accommodate the new bulges 'wherever'.