Identify this tool

I’ve acquired this air stapler but there’s no identifying markings on it. I want to locate an owners manual so I can begin using it. Any assistance would be greatly appreciated.![20190903_211110|690x387]

another pic

I can see that you don’t have much to go on.
The label on the front may be your best clue as the circled R - indicates that it may be the manufacturer’s trademark. From the picture its a bit too hard to make enough out to tell - but maybe you can look with a magnifying glass. The little elongated-rounded end spot on the side - looks like it may have once held a name - and Senco uses that shape on some of their tools.
Looking at the vintage - it might be a Senco - but could also be a Duo-Fast or Paslode to name some brands that have been around for some time. It does not look like a Bostitch - but could well be some European brand - as Italian (like Maestri) and German (like BEA) were popular with the upholstery trade.

I would also say it’s not a Bostitch as the body has NO YELLOW on it anywhere. All Bostitch stuff even the older stuff all had some yellow on them. Likewise I don’t recall seeing anything SENCO that didn’t have red on it.

I think your logo on the top of the tool might be a stylized F. Duo-Fast - started life as Fastener Corporation in the late 40’s after the war. They started in the automotive basis - and were the frist pneumatic stapler on the market. So if I was to bet anything is that you have an early Fastener Corporation pneumatic stapler - and it’s possible it’s from the 50’s.

and yes I looked up Duo-fast corporate history. the rest is a guess.