Corpsman Mark I pellet gun .22 caliber.  Looks like 1970s vintage.  It shoots!  The CO2 cartridge cap leaks, so I ordered a new o ring kit off Amazon.  Can anyone tell me anything else about it? Thanks!

I have one just like it. I bought it new back in the 70s when I was about 10. That thing was scary accurate. Some have an adjustable trigger. The trigger is the best of about any airgun made back then. Great trigger. I want to say about 450fps with pellets, it was enough to kill squirrels at around 25 yards.

Very accurate with an amazing grip.

Mine needs an overhaul. The oring at the grip plug was bad, but I replaced it and it still leaked. Other seals inside the gun have gone bad. I need to send it off. I asked on here a while back where I could send it, and was told where but I can't remember. The guy pretty much specialized in them, and offered upgrades too.

Some of them came with an adjustment where you could increase power, and I think I remember than he offers that, as well as tuning the trigger, and making yours adjustable even if it wasn't originally.

I really need to dig mine out and send it off.

Great find.

Ah, I just saw where yours is a .22. Yeah, that is much better. Mine was the .177 version.

I'm not sure on the velocity of the .22 version, but I actually think it was very close to the .177 version.

When you get the pistol fixed and have a charge in it and pull the trigger, it feels completely different. The trigger feels sort of dead or springy without a charge.

It actually shoots, it just makes a hissing sound for a few seconds after you put the gas canister in.  I only got to try a few shots yesterday, but I am hoping to spend some more time with it today.  Thanks for your input and advice!

Does it have the two position cocking: low and high power?  Some of them (if not all) do.

That pistol in .177 is capable of doing reasonably well in 10 meter pistol shooting.  They are that accurate.

In .22 you cannot use it in formal 10 meter competition, but the power level will be low enough that any 10 meter backstop would be adequate.

CO₂ is very consistent when the temperature is also consistent. If you take your time between shots the velocity will be quite consistent, and hence the level of precision.   If you shoot one day when it is chilly, and another when it is warm, you will find a velocity change.  CO₂ is at its best between 70 and 78 degrees F.