by Tom Gaylord
Writing as B.B. Pelletier
Today’s report is a guest blog from reader Ian McKee who writes as 45 Bravo. He’s going to tell us about the Crosman Mark I pistol he recently acquired and what he did to fix the leak it came with.
If you’d like to write a guest post for this blog, please email me.
A history of airguns
Over to you, Ian.
Crosman Mark I and II reseal
by Ian McKee
Writing as 45Bravo
This report covers:
- Just kidding!
- Four major changes over the years
- I got this one cheap
- It’s mine!
- Bringing it back to life
- BB’s end cap
- Resealing both caps
- How did it go?
- Outer barrel removal
- Wrong o-rings
Back in December 2018, and January 2019, B.B. reviewed a classic Crosman Mark I pistol in .22 caliber.
There were many comments about how it worked internally, and how the power adjuster worked, so today I thought I would give you a little peek inside the gun.
Here is your peek of a disassembled pistol. This is actually a Mark II I photographed some time back. The parts of the two pistols are identical except for those pertaining to the caliber.
Thank you, that concludes today’s blog.
Just kidding!
I could not do that to you. Here is a synopsis to refresh your memory.
The Crosman Mark I and Mark II (.22 and .177 calibers, respectively) pistols are airgun versions of the classic Ruger Mark I and Mark II .22 rimfire pistols. They share the same grip angle, sight profile, and overall profile of the iconic Ruger rimfire pistol.
Ruger’s Mark I pistol.
All Crosman Mark air pistols retained an adjustable trigger throughout their production run, which was 1966 to 1986, but had other changes in their design over the years.
Four major changes over the years
The flip-style piercing cap was changed to a button-style piercing cap, similar to what’s found on the Smith & Wesson 78/79-series air pistols.
The metal bolt guide that was secured in the frame by a screw on either side below the rear sight was changed to a plastic bolt guide that is retained by 1 screw that’s hidden under the rear sight blade.
The power-adjusting screw that was located under the barrel was eliminated.
And to hold the grips they changed from using screws with countersunk heads to screws with flat heads, as shown.
There are two different grip screw head profiles and grips that match them.
If you use the countersunk screws on grips made for flat-head screws, you will crack them, and it is not easy to find replacements.
There were some other minor changes over the years, but these were the big ones.
I have been a big fan of these pistols over the years, and have owned and resealed more of these than I have of the Smith & Wesson 78/79G series. In my opinion, the adjustable triggers of the Crosman guns are better than the adjustable triggers of the S&W guns. The engineer that designed these air pistols later had a hand in the design of the Smith & Wesson guns.
I got this one cheap
I saw this pistol online with a $50 or best offer price tag, and no photo. These two things together usually tell me to run away and let someone else take the chance.
I got to thinking I could always use it for parts, so I took the bait and contacted the seller. I found out he lived not too far away, and decided on a face-to-face look at the pistol.
He sent some fuzzy photos by text, that didn’t help my feelings about the deal.
In the ad he said the gun had leaks. When I finally saw it, it was one of the roughest Mark Is I have ever seen. It had been repainted several times, and at some point, someone had covered the bare spots with a permanent marker to make it all black again.
Right side.
Left side.
I put a CO2 cartridge in it and it vented all of the gas out of the piercing cap while I shot it a few times. [Editor’s note: Doing this in front of the seller is a big negotiating tip, because it emphasizes the fact that his gun doesn’t work!]
From this short examination I knew 3 things:
1. This was an early model Crosman Mark I in good mechanical condition.
2. All of the parts were there.
3. It did NOT leak out of the barrel, when it vented the gas.
It’s mine!
I made a ridiculously low offer, and he accepted. When I got it back home and on the bench, I started by cleaning off the permanent marker with alcohol.
I knew it was an older model, but did not realize how old, as in serial number 000659! There is not even a date code.
This is an early Mark I.
I now own one of the first ones made and also one of the last ones made.
Bringing it back to life
I put a second CO2 cartridge in it to check it out on the bench. It vented the gas in about 30 seconds and it all came from the piercing cap. That told me the valve seal was still good.
I shot it over the chrono as it was venting. The gun was cold from the CO2 cool-down, but it still registered 485 f.p.s.
Most times the leak is because the tiny o-ring in the piercing cap deteriorates. The piercing pin moves up and down in the older models by a lever. You flip the lever one way to pierce the CO2 cartridge, then return to its normal position to let the CO2 into the gun.
Some online disassembly guides say you have to remove the snap ring at the bottom of the cap and then drive out a roll pin. That is the hard way. The easy way is to use a 3/8-inch wide (9.5mm) screwdriver blade in the slot inside the piercing cap. Use it to unscrew the cover that contains the 006-sized o-ring.
This cover is threaded and acts as a screw to hold the small o-ring in place. It looks in the photo like the piercing pin will prevent unscrewing it, but the end of the pin is actually below the screw slots. Remove this cover. In a moment I will describe and show a newer style end cap that has some different parts and comes apart differently.
With the cover off, use a dental pick to remove the old o-ring. It is probably hardened and will break into fragments when you pick at it. It may not even look like an o-ring, but it is tight around the base of the piercing pin.
Once all the small pieces are out of the cap and the o-ring groove is clean, lightly lubricate the new o-ring with your choice of lube, center the new o-ring over the piercing pin, and push it into its recess. Then screw the cover back into place over the o-ring.
The screwdriver fits into the slots on either side and unscrews the cover. The tip of the piercing pin is below the slots. The cap looks brassy in this photo but it is really steel.
This picture with a different angle shows how the o-ring sits at the base of the piercing pin. read more
