Spent years looking for one-to no avail. The only gun-maker I knew of who could squeeze more than one charging system (spring/piston /pump-up or a CO2 operated mechanism) into the one gun frame was........Mr Kenneth Pitcher of Healthways.That is why his 'Western Plainsman' is such a dinky collectable! Having said that, nowadays it seems skilled artisans have no trouble converting spring/piston powered units like Webleys and Walthers,into CO2 operated guns! Also,a number of USA-made products have and are being offered as pump-up or CO2 powered guns-even CO2 or PCP ones.Where will it ever end?