Challenger Plainsman CO2 pistol

Challenger Plainsman CO2 pistol (.22 cal) 

These pics copyright Holts Auctioneers.

Challenger Plainsman CO2 pistol stripdown 

With thanks to Jack.

Challenger Plainsman CO2 pistol ad & instructions 

With thanks Jack.

Challenger Plainsman CO2 pistol conversion to PCP 

With thanks to Jack.

He says:

This 0.22" pistol was made for only a few years in the late 1950s and was originally designed for 8 gram CO2 cartridges, Carbon Dioxide isn't really my thing however so I've converted it for pneumatic use. It was purchased non-functional but complete except for a missing front sight.

New endcap machined and valve resealed with Delrin:

Detail of the power adjuster, by unscrewing the central bolt from the hammer mass one can increase or reduce the depth to which the valve is struck:

Front sight installed along with the parts that are not used, namely the cartridge piercing pin, cartridge itself and cartridge cap:

First test with compressed air, this thing is loud!

Slow motion firing showing the trigger mechanism and the considerable hammer bounce at full power:

He adds:

[I] machined a new end cap with a fill nipple. That was a minor headache in that the thread size is 27 TPI and my lathe only lists change gear combinations for 26 and 28.

In case it will help anyone for a CX708 lathe with a 3mm pitch lead screw I used 65, 120, 127 and 55 gears on positions A, B, C and D respectively.

I've taken it to 1800 psi maximum and I don't think I'll go beyond that, I'm sure the cartridge tube and valve body can take that but it's the threading in the pot metal chamber that's holding everything together so I don't want to push it too far.

Using 14.3 grain Crosman pellets and with the power adjuster backed off I got the following muzzle velocity values in feet per second when starting from 1500 psi:

404 - 401- 389 - 394 - 384 - 379 - 365 - 363 - 377 - 343

Obviously CO2 is a denser power source and ideally a larger chamber volume would be needed but it takes no time at all to pressurize with a hand pump so I'm fine with this while leaving the original pistol relatively unmolested.

Challenger Plainsman CO2 pistol (extended target barrel) 

With thanks to John M.