from Bianchi's website we find they lay claim to the thumbsnap safety strap in the mid-ish 1960's.
"The company grew out of John Bianchi's desire to create an effective holster that he could wear on duty as a police officer. That was just the start of the many innovations to come. The widely used thumb snap feature included on the original Bianchi Model 5BH/5BHL, as well as the 19/19L series, was first innovated by Bianchi in 1960, and has revolutionized holster designs ever since. "
https://www.safariland.com/bianchi-resources/bianchi-history.html-------------------------------------------------
howver, noted holster historian and guy who used to work for people, Red Nichols states
http://smith-wessonforum.com/gun-leather-carry-gear/540473-history-bianchi-5b-holster.html"I suppose the real story of the 5B is the story of the thumbsnap. John has claimed early and often to have invented the thumb snap, but the patent for it was filed by Mr. Bucheimer and the lesser-known Mr. Kippen (who worked for several companies and apprenticed at Heiser) before John took up holsters in 1958 after leaving the Army.
John's version appeared not in his earliest 1963 Protector Brand catalogue but in his 1966 Bianchi Holster catalogue. Ten years is a long time in patent history; where one man beating another by a single day is decisive. "
so I looked up patents and found this one by Herr Bucheimer, showing a thumbsnap safety device filed jan 11 1957
http://www.freepatentsonline.com/2917213.pdfbottom line, it's very modernsich and 5 years off a fifty year old timeline ain't nothin.
yhs
prof marbles