This is a Crosman MK2 .177 caliber CO2 pistol. Got it several years ago from highly esteemed airgunner "Wacky Wayne".
I've got a MK1 (same gun, but .22 caliber) also, but this MK2 won the toss for further modification largely because the bolt has already been replaced. And since it's not a stock gun anymore, it's easier to justify additional work.
Wayne sent the gun with no explanation as to the exceptionally machined loading bolt. It's made from stainless steel and the knurling is so sharp and precise, it's obviously cut and not forged.
I think the plan is to fit a longer barrel, and replace the tapered barrel cover with something that looks more "bull barrel-esque". Got started by removing the barrel nut at the front of the shroud. I used a Shimano bicycle tool normally used to hold chainring nuts. I suppose it could correctly be termed a "peg spanner".
Notching a steel bar would also work.
With the nut removed, the shroud slides off the barrel. The lower lug on the bottom of the shroud acts as a base for the hammer spring. Most of the bull barrel replacements I've seen start by cutting the shroud off just in front of the ring. Saves the hassle of making (and attaching) a new lower lug.
The stock MK 1 and 2 barrels aren't very substantial. 3/8" diameter.
Removed the setscrew. The setscrew pushes the barrel downward to seal against the transfer port.
Unscrewed the rear knurled barrel nut.
And the barrel slides out. As you can see, this is a "tensioned" barrel arrangement. The barrel is threaded at each end with the shroud in between.
More soon.
