The Webley Fosberry automatic self cocking revolver was featured in "the Maltese Falcon" and in the sci fi film "Zardoz".
I don't remember if they ever showed the pistol fired in Zardoz.
I wonder just how they could make a Webley Fosberry operate if using blanks?
In Hatcher's notebook he wrote of several attempts to convert 1911 pistols to use blanks, and these attempts ended badly with blown up barrels and/or damaged slides.
I suspect this was due to trying to produce enough recoil by jet effect of muzzle blast alone to operate a locked breech action. Blowback actions are more easily converted.
Most blank firing prop guns these days are purpose made devices rather than conversions of real firearms.
Two reasons why blank firing guns have been replaced by non firing dummy guns and CGI muzzle blasts is that when filming on location a film company must get clearance from a local fire marshall before using any pyrotechnic device, and must obtain a special insurance policy.
Materials coming in contact with the smoldering particles or wadding from a blank load can catch fire hours afterwards.
Another reason is possibility of hearing damage to actors when blanks are fired indoors.