Monday, December 7, 2009

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.


Anonymous said...

Derrick,that helps alot!!I'm that guy that asked.Mine is the Ted Williams variant from 1958...thanks

derrick38 said...

Glad you found it. Sorry I couldn't get to it sooner. Been working like a dog and traveling on all my days off. Need to make some new grips for it but the woodworking stuff is in the garage and it's in the 30's. Soon.

Anonymous said...

I saw your blog on your Crosman 150 and really enjoyed it. I just acquired one myself and did not realize how old it was. Your dis assembly steps helped a lot and was neat to see what I was getting into before I took it apart. I had to replace the seals in mine and found that seals in a kit from harbor freight work perfect. The item Number is 67580 for the assortment of o-rings. I already had the Metric, american, and AC seals in my cabinet and figured I'd see if those work before I ordered a seal kit. And so far it worked like a charm. The old seals were dry but the one that really leaked was the one on the air chamber inside. Most people seem to only have the cap seal leak, mine was just the opposite.
I wanted to share this little bit of information to to hopefully help others. Thanks again for some great information


Anonymous said...

i rebuilt my grandfathers for a dollar with o rings from autozone

Anonymous said...

How did you get the "Small Tube Plug" out? Mine seems to be stuck.

Anonymous said...

Thanks for the photos and instructions! I'm trying to rebuild my 150 and couldn't figure out how to get the thrust pin out. You saved me a lot of grief!

Anonymous said...

Thanks for good instructions. Do you if its possible to convert to hi pac?

Anonymous said...

I really appreciate your work here....Normally I can tear-apart/rebuild anything! I was genuinely frustrated trying to disassemble the valve assembly....
Your "how to" was 100% helpful! :-)

Anonymous said...


Anonymous said...

I followed all of the steps and the leak is about 80% better. I still have an issue with a small amount of gas leaking constantly from the barrel. :(
Any suggestions? -Greg

Anonymous said...

If you replaced all the o-rings and it is still leaking it is most likely the seal inside the exhaust valve assembly. Not the o-ring but the flat seal inside the brass valve. Tim at Mac1 sells them as a kit, but he recommends trimming the seal surface on a lathe so it is flat and flush with the brass valve body.

Corky Landrum said...

I can't get the original grips to come off and i don't want to break them. Any tip's and do you have a pic of the back / inside of the grip so i know what im working with. Thank you so much for everything.

Anonymous said...

Very helpful, especially getting the pin out and also making sure I didn't end up with a bunch of parts instead of a working gun. I found in my collection an 8-32 brass screw with a an unthreaded tip that I used to push the pin out by just screwing into the sight retaining hole. I also fond that just gently tapping the tube I could move the entire valve assembly away from the pin, no need to push it out of the way. I disassembled mine to fix its leaking valve. The seal was hard as a rock and I spent about an hour trying to remove it from its deep groove without damaging the probe body. I filed tiny brass knives and chisels from bar stock and painstakingly chipped away. Everything else went smoothly.

An Omonys said...

When I remove the grip screws on both sides the one-piece grip it just slides off with no obstructions and no special tricks.

Anonymous said...

I replaced all the seals with the proper seals, but my crops an 150 still exhausts all of the CO2 after the first trigger pull. It looks like it's all coming out through the breach hole the proper way, but the gun isn't holding the CO2.

Any ideas on how to fix it? Is there a place I can send it to have it worked on.

Bernadette Reilly said...

I rebuilt my 150 with proper o rings as well but it still leaks out fastthrough the end of the barrel. Your pictures saved allot of time and really made the strip down and assembly a breeze. Any suggestions?

Anonymous said...

Thanks very much for the info. Much easier to follow this guide than the Crosman one I had. It leaves out the thrust pin part. I wasn't sure how to get at it until I read this so that's really appreciated.

Thanks again