Frank Clarke – airgun genius. The conundrum of one of his last inventions.

[ccdjg]

One of the many puzzles in the field of vintage airguns is why Frank Clarke bothered to introduce a spring-loaded “pusher” loading pin into some of his first model Briton pistols. I have had a Briton with such a pin for many years and thought at first that the pin was just a one-off from an amateur hobbyist, but other examples have since come to light (possibly as many as five) and we can now be confident that the retractable pusher pin was indeed the brainchild of Frank Clarke.

But it was a development that never really made the grade. The retractable pin screws into the breech in the usual way with these push-barrel pistols, and pushes the pellet into the barrel. Once it is screwed in place, the spring-loaded end knob can be used to push the pellet in even further. The knob then returns under spring pessure to seal the breech. The following picture shows a normal Briton pin, together with the spring pusher pin in its relaxed and compressed states.




The puzzle is why did a Frank Clarke, an undoubted genius when it comes to air pistol design, bother with such a complication ? It would have been expensive to make compared to a traditional pin, and seems to achieve nothing that a normal pin can’t do. I have puzzled over this for some time and reluctantly came to the conclusion that it was an uncharacteristic lapse on his part and just a passing fancy that served no real useful purpose.

Then one night, thinking about nothing in particular, out of the blue I had a flash of inspiration and I knew what the retractable pin was all about. Far from being just a whim on Frank Clarke’s part it was an extremely useful invention, brilliant in its simplicity. In fact it was something that should have been patented and fitted to other push-barrel pistols, so why he didn’t take it any further I don’t know.

No, I am not going to tell what the real function of the retractable pin is – not yet anyway.

I thought it would be interesting to challenge you, to see if you can pit your wits against Frank Clarke and work out what he was really up to. Like all good ideas that are really obvious once pointed out, it takes a genius like Clarke to spot them in the first place.

[rancidtom]

It gives a lower power option. Lowers the effective compression ratio, increases "dead space" volume and effectively shortens the barrel.

[Benelli B76]

Don't think anyone would like to make these lower power than they already are. How does the air get by the larger diameter pin ?

Baz

[ccdjg]

No, nothing to do with altering lost volume or power level. Much more significant than that.

[averageplinker]

In-built pellet sizer/former?
Used to push the pellet past a transfer port?
Rich.

[johnbaz]

I always thought that pushing a gas through a smaller opening made for higher presure!


John

[averageplinker]

Does it allow 2 projectiles to be loaded? First one goes in then is pushed in deeper, out comes the pin and in goes projectile 2???