I've been studying this for a while and have had opinions but I'm always looking for proof or at least apparent evidence to back up my thoughts. Here is what I've come up with so far.
Heiser used a model numbering system that consisted largely of 3 digit numbers starting with 1 up until the late 1910's. Their catalog number 14 was the last catalog that I've seen that used that system. Catalog # 19 had the system that used 3 and 4 digit numbers- the 3 digit numbers started with 4 for plain finish, 5 for basketweave and 7 for floral carved. The 4 digit numbers started with 1 or 2 and were usually variations of the 3 digit numbers indicating extra features. Shoulder holsters continued to use the 3 digit numbers starting with 1 (2 for floral carved examples). These model numbers were used until the 1950's. One of my # 19 catalogs has a factory representatives stamp on it and a hand written receipt from the rep dated 1922 in it so that's how I dated the model number change to the late 1910's.
The 3 H stamped rivets are another indicator of age. They were used on the early model number holsters I have and the later system as well, sometime up into the 1930's. I have a holster made for a .38-.44 Outdoorsman with the old style rivet, I think that revolver came out in 1931 and that is probably the latest holster I have with that style of rivet. So holsters with that rivet pre-date the 1930's.
The black enamel and brass 3 H snap is another indicator. They were used prior to WW II, they switched to a brown enamel snap after the early snaps were used up. The earliest catalog I have that shows both the 3 H snaps and the brown snaps is # 40. A copy of that catalog came to me with a Heiser post card advising a price increase dated April 1942. I have a letter from Heiser to Evaluators Ltd. advising a price increase that refers to pricing in catalog # 40, the letter is dated June 1950. So the brown enamel snap came into use in the 1940's.
The elongated Heiser Denver logo stamp is sometimes cited as an early stamp that dates the holster. I have at least one example of a holster that wasn't introduced until the 1950's that has that stamp so I don't consider it an accurate means of dating the holsters. The oval stamp was used throughout the 1900's. There are other stamps but they are uncommon and sporadically used.
Those are my thoughts on dating Heisers with the little evidence I can muster. I'd love to hear any of your ideas about this.
Regards,
turnerriver