Crosman 150 Service

Bought a 2nd variant Crosman 150 (.22 caliber) at a gun show a couple months ago. Seller said it came from the estate sale of a former bullseye pistol shooter. Guess that explains the handmade target grips. Unfortunately, the grips fit my hand better than they fit the gun. The right side is a bit wobbly on the grip frame.

The 150 is notable because it's the first CO2 pistol from Crosman to use the standard 12 gram cartridge. It's essentially the father of the current 2240/2250 guns.

The Crosman website says the second variants were made from 1958 through 1968. If that's the case, the gun is older than me by at least a couple years.

Originally, the 150 would have come with a wrap-around brown or white one-piece grip. The trigger and trigger shoe are from my last project about a week ago. I did a super fast tear down a few weeks ago after a reader asked a disassembly question on the Pyramyd Airgun blog. It was late and I didn't have time then to take the pictures. I made the time tonight.

Unscrewed the end cap. Good, there's no CO2 in the gun.

Removed the grip panels--not a necessary step unless you're going swap the trigger spring.

Unscrewed the 2 grip frame bolts...

and the grip frame comes right off.

Don't lose the small safety spring and the ball bearing. They reside in the hole on the left side of the frame just behind the trigger. Ball goes in first, spring sits on top and pushes the bearing downward against the safety.

Removed the rear sight.

And the bolt comes right out. Not shown--the breech plug (small cap) pulls off the end of the upper tube.

Next, unscrewed the breech bolt screw and removed the breech cover (Crosman calls it a "loading sleeve") and the bolt.

Like so. Sorry. Blurry.

The hold down screw came next.

And the barrel/breech assembly lifts right off the gas tube. Don't lose the transfer port seal. A current 2240 transfer port seal is 100% compatible. Crosman part #130-036

This is the only trick. The "small tube plug" is pinned in place.

The trick is how do you get the pin out? The valve stem is in the way.

I used a transfer punch to push the valve stem forward toward the front of the gas tube.

With it pushed forward and braced against the workbench, I slid a pin punch through the hole above for the hold down screw and removed the transfer punch while keeping downward pressure on the pin punch. The pin punch slipped behind the end of the valve stem and rested on the top of the thrust pin..

A rap with a hammer and the thrust pin pops free.

"Small tube plug" and the thrust pin.



Note that the holes are offset in the tube plug. The offset goes to the front of the gun.

A piece of 1/2" plastic water pipe allowed pushing against the rear of the valve body without touching the delicate valve stem. Valve must be pushed forward to be removed.

Note the o-ring at the front of the valve. The early Crosman CO2 guns seal the cartridge in the tube. The new Crosman guns seal the cartridge only against the face of the valve.

A strap wrench unscrewed the valve body without marring. Some 150 valve diagrams show a few more components, but this is all I found in mine--a check valve spring, piercing pin, and valve stem. Clean and lube everything with pellgun oil.

When reassembling the valve, the threaded hole at the front for the grip frame must be 180 degrees from the exhaust valve hole. I installed the grip screw and sighted it against a transfer punch in the exhaust hole.

Lube the tube body o-ring on the valve and slide it home. Ensure that the exhaust hole lines up as well as the front grip frame threaded hole.

Like so.

Installed the front grip frame screw to keep the valve lined up.

Small tube plug--remember the offset faces forward--and the larger, unthreaded hole for the thrust pin goes on the bottom.

Seated the thrust pin and tapped it in gently with a small hammer.

Reinstalled the barrel/breech assembly (don't forget the transfer port seal between the tubes). Used a transfer punch to keep the rear holes aligned.

The rest of the reassembly was a straightforward reverse of the above steps.

Don't forget to lube the o-ring on the cap.
Before disassembly, the gun was working and I didn't want to risk damaging any of the seals by removing them to take measurements. If you need new seals for a Crosman 150/157,  call Ron at Bryan & Associates.