Tuesday, May 5, 2009

Derrick's Crosman 180 Repair Part 1

One of my customers, James, came in last week and gave me an old rifle: a .22 caliber Crosman 180 CO2 gun. He said it worked just fine the last time he'd shot it--back in 1978! He remembered the burglary I went through last year and wanted to help rebuild my airgun collection.

The gun is in exceptional cosmetic condition. The bluing is about 90+% I think we figured the gun was from around 1962--mainly by dating the second variant trigger as well as James' recollection.

The Crosman 180 is essentially a shorter and lighter version of the 160. The 160 rifle uses two 12gm CO2 cartridges, the 180 gets by with just one.

A generous amount of Crosman Pellgun oil and about $5.00 in CO2 cartridges proved that the gun leaked like a true champ.

Disassembly time.

Remove the CO2 end cap, the safety and the nut/washer from the locating stud.

Action lifts right out of the stock.

Remove the trigger housing bolts.

A threaded bushing comes out next.

Remove the rear breech bolt.

The hammer assembly slides out. Note the mushroom shaped breech cap.

The hammer plug slides right out.

Inside the rear of the breech, the bolt handle is held in by a screw. Loosen it a couple turns and the bolt handle pulls right out.

Just for the record, this is not the stock bolt handle. I turned this one on the lathe to replace the damaged original. The ball end was gone from the original handle. Initially I was going to make an exact copy, but then decided to add some heft.

Loosen the barrel band and it slides forward off the gas tube.

Remove the front breech screw.

The barrel, spacer, breech seal and gas tube can now be separated.

From the front end of the gas tube, the face of the valve is slotted for a special tool.

I made this from a piece of 3/4" diameter tool steel. A similar tool is currently available from Bryan and Associates. It's their tool #T-9 "valve body disassembly tool".

This is out of sequence, but it shows how the tool fits into the end of the valve face. Here's the important stuff: The valve is made of 2 pieces of brass threaded together at the o-ring. In the gun, the rear of the valve is held fast by the locating stud. The valve tool is then used to tighten the front of the valve--this expands the o-ring outward sealing off the gas tube. In the older Crosman CO2 guns, the valve does NOT seal on the end of the 12 gram cartridge. Because of this, a bulk fill cap can be used with an adapter to charge the gun from a paintball tank--eliminating the need for 12 gram cartridges altogether.

Back to the task at hand. Use the valve tool to loosen the valve a couple turns. This takes the pressure off the o-ring.

Now the locating stud can be removed. I grabbed the stud in a padded vise and turned the gas tube to unthread. The stud thread is #10-32.

Valve can now be slid out of the gas tube.

Old seal on the left. It looks and feels like a nylon washer. It's rock hard and has perfectly square sides. A new o-ring seal is on the right.

Time and pressure. Had to crack the old seal to get it off the valve thread.

Here's the old standard Crosman valve. They used this in many CO2 guns. I didn't pull the felt from the inside front of the valve. It was in great shape and I didn't want to tear it getting it out for a picture.
Spoiler: Replacing the valve o-ring and reassembling was a complete bust. The gun had a weird, semi-serious valve problem that took several days to work out.

More to come in a few days.


Unknown said...

Thank you Derrick we have our 180 in pieces on our pool table and your pictures with descriptions helped. Jay n moe

kale said...

Ok I saw you had the air chamber out and said there was s piece of felt in the front.... Do you mean where the plunger is? Cause I have a 160 and when I shoot the co2 leaks right out the chamber... Any help would be nice

Anonymous said...

It seems the set screw for the hammer assembly is missing in mine . Is there a replacement screw like a set screw to use in its replacement ?

Anonymous said...

Thanks to your blog's I've been able to replace all the seals and lubricate my vintage 180 that has been sitting in my closet since the mid 70's, I was even able to fashion the valve tool using 3/4x1/8x36in flat aluminum bar [Local Home Depot]and minor side/filing and cutting the center notch similar to the one you show under your Crosman 160 instructions (Volvo's designed) that worked perfectly.

I'm finishing up now and noticed my adjusting cock screw is dialed way in and in your picture yours is dialed all the way back.

Do you know which is the 'default' factory position Crosman mentions in the manual? since this adjustment is not supposed to go behond 7 turns max in either direction?

Hope you reading this ..Thanks

Unknown said...

hey i know this is an old post but can you explain how to remove the safety. I just got my 180 and don't want to pry on anything i shouldn't.


derrick38 said...

Joel, try here:


Unknown said...

Was the face of the valve already slotted or you had to make a slot for the tool?

derrick38 said...

John, the valve face has a slot from the factory. It's necessary so you can tighten the valve halves together inside the tube to expand the o-ring to seal the gas tube.

Unknown said...

Mine has no slot, I looked with a magnifying glass with a flashlight. Also the adjustment hole for co2 adjustment with the allen wrench is not there. Is it possible mine is a really early model?

derrick38 said...

John, I'm sorry, but I don't know. This is my only experience with a 180

terry said...

Where do you think I could get a replacement butt plate for my old Crossman 180 ?
Mine was sold as a J C Higgins. Terry kiowa002@hotmail.com

derrick38 said...

Terry, I'd probably hunt eBay for a similar looking, and similar sized plastic plate. Expect to do some fitting.

Anonymous said...

Thank you for this breakdown of the 180 pellgun i have aquired one tgat has the same issue of leaking. Looking forward to it greatly when it's back in working order.

Unknown said...

Hi Derrick38, do you know the proper size of the allen bolt that adjusts the hammer spring? When I took mine apart the allen bolt is sticking way out (maybe 1/2 inch) I see on your pic that it dosen't appear to be out at all. I also watched a vid from TOM Cat AG's and It looked like his was not sticking out when he removed it. I have a down load of an old manual and it says use a 6x32 allen wrench. Which I don't have and seems way to big. Any advise would be appreciated.

Bill C!

Anonymous said...

Make the special tool from a 11/16 spade bit by grinding off the tip

Unknown said...

Hello I just found a 180 pellgun in my dad's safe can anyone tell me what size cartridge it takes seems like the 12 gram is to small? Thank you much

derrick38 said...

Does it look like you can fit two cartridges? If so, you might want to look up the Crosman 160 and compare the gas tube lengths. Maybe the longer tube was installed for some reason. Shoot me a pic to my email address.

Unknown said...

Turn it half way while pushing on the other side of the safety you will feel it move in when you hit the sweet spot then work it the rest of the way out