Ive just been reading the Blue Book Of Airguns, 4th edition by R. Beeman and J.B. Allen (ISBN no. 1-886768-47-1, an ideal Christmas gift for anyone interested in all types of airguns ) and came across the Shark Manufacturing Co., Buenos Aires, Argentina entry. Quote:

'Shark began in 1975, producing underwater spear guns, using elastic bands or a GAS-SPRING mechanism .

In 1979, a unique application of this gas spring mechanism was used in the development of the Shark CQ air rifle which use a conventional barrel cocking system but have a vey interesting, special multiple cocking capability. A single barrel cocking compresses the gas-spring to ordinary power potential; two strokes triples the power.'

Has anyone ever seen or used one of these gas spring rifles? I though Theoben had invented the gas spring system.