Resealing an Old (and Very Special) CO2 Pistol

[paulleve]

My dad passed away in the spring, and while cleaning the house I found something I hadn't seen in at least 30 years, his Smith & Wesson 78g .22 pellet pistol. It was the first "real" gun I shot as a kid, so it brought back lots of fond memories. Unfortunately, the seals were absolutely shot, which is why it had been packed away unseen for so long. (The 78g is almost identical in size and weight to the S&W 41 target pistol. A 79g was also offered in .177.)



After researching seal kits I opted for the best one I could get, ordered through MAC1. It came with six seals and an upgraded exhaust valve assembly.





Thankfully the Internet has lots of info available, and between two websites and one Youtube video I was able to disassemble, install new seals, and reassemble the pistol without any parts left over! (This pic was after I rebuilt and reinstalled the valve assembly.) Total time was about three hours. If I had to do another, I could in about half that time.





The original seals were in various states of decay. Only one came off in one piece, but it's hard and dry. One special tool was required to make life easier, and this was made with an old drill bit and some Dremel time.





I can't tell you how happy I was to smack the piercing knob and have it hold pressure! A quick trip outside for one or two - or forty! - test shots, and I can say it was all well worth the time and money invested.

While going through paperwork I actually came across the old style FA-10 that was used back in the day. Dad bought this at The Fair in Spencer, MA, in February '76, and had to have a pistol permit in order to do so! He actually wanted to buy a Single Six and this on the same day, but he couldn't so he bought them a day apart. I was really young at the time and can't remember if he said it was a store policy or something with MA laws that wouldn't allow two handgun purchases on the same day.

 

[appraiser]

it's never too late to have a happy childhood.

 

[greencobra]

well done!

 

[Mountain]

Awesome!

 

[Len-2A Training]

Awesome.

I have the 79G, somewhat disassembled due to failed seals. I never repaired it, but this post motivates me to look into it.

It was also one of the first guns I ever bought so I could practice in my backyard. I bought it at Ivanhoe's in Watertown Square back in 1976. I still have the tissue-paper FA-10 for it too.

 

[Uzi2]

 

[silversquirrel]

Excellent! I picked up a nice 79G, .177 many (20?) years ago, and restored it.
Great shooter. Its due for a seal refresh. The seal in the c02 piercing mechanism doesnt hold any more. Ill try the kit you used!

 

[dezignguy]

I had the same one about 30 years ago. Wish I still had it. The seals wore out and it got put on a shelf somewhere.

 

[paulleve]

Excellent! I picked up a nice 79G, .177 many (20?) years ago, and restored it.
Great shooter. Its due for a seal refresh. The seal in the c02 piercing mechanism doesnt hold any more. Ill try the kit you used!

There are some seal kits that are a lot cheaper on Ebay, but the sources I found seem to mostly recommend MAC1 due to the higher quality seals and improved exhaust valve. I put a new CO2 cylinder in it and pressurized the system, then stuck it in a sealed Ziplock to see if there's any leakage. It's been four hours now and nothing seems to be getting by the seals. I'll eventually let it sit for a week or two to see if it holds pressure. But that's after I thoroughly enjoy shooting it this week!

Here are the two sources I relied on the most:
Pyramid Air Reseal Directions
Youtube Video

The MAC1 seals are quite rigid, so heating them up with a hair dryer is necessary to give them the stretch to fit around the parts. Those small ones are especially difficult to get in place. My valve assembly wouldnt come apart like it's supposed to, so I needed to apply a little heat with a propane torch. Once it got hot enough the inner part of the valve just slid right out. Other than that, it was just a matter of disassembly, clean up, lubrication, get the new seals in, and reassemble.

 

[smokey-seven]

I was able to disassemble, install new seals, and reassemble the pistol without any parts left over!

I was really young at the time and can't remember if he said it was a store policy or something with MA laws that wouldn't allow two handgun purchases on the same day.

MA gun laws have changed so many times, some for the good and mostly for the bad. I can remember having to fill out paper to buy ammo and back then they required a LTC to buy pistol ammo or at least an FID for rifle ammo. I'd always ask if the 22 LR was pistol ammo or rifle. Store policies are always all over the scale and vary from one store to another even if it was the same franchise. I cannot recall a MA law requiring one hand gun a day.

 

[nstassel]

that gun is a beauty. I've never seen one before and I love the model 41 and owned three.

 

[mac1911]

There are some seal kits that are a lot cheaper on Ebay, but the sources I found seem to mostly recommend MAC1 due to the higher quality seals and improved exhaust valve. I put a new CO2 cylinder in it and pressurized the system, then stuck it in a sealed Ziplock to see if there's any leakage. It's been four hours now and nothing seems to be getting by the seals. I'll eventually let it sit for a week or two to see if it holds pressure. But that's after I thoroughly enjoy shooting it this week!

Here are the two sources I relied on the most:
Pyramid Air Reseal Directions
Youtube Video

The MAC1 seals are quite rigid, so heating them up with a hair dryer is necessary to give them the stretch to fit around the parts. Those small ones are especially difficult to get in place. My valve assembly wouldnt come apart like it's supposed to, so I needed to apply a little heat with a propane torch. Once it got hot enough the inner part of the valve just slid right out. Other than that, it was just a matter of disassembly, clean up, lubrication, get the new seals in, and reassemble.

MAC1 has been a great resource for air gunners for many yesrs.
His super tuned up rifles are something to see.
Im a sucker for a classic air gun.
Those SW 79s do not show up to often.
I would reorder a few more kits just to have.
I like the crosman 140, 1400 pumpers

 

[paulleve]

Here's an update on the reseal I performed on my dad's S&W 78g. The last time I shot this was about seven weeks ago, and I left it charged with a partially used cylinder. (Directions say this is the way to store it.) I took it out tonight after work, and managed to pop off a bunch of pellets before having to throw in a new cylinder. It's pretty amazing that a resealed 50 year old pellet gun is this tight! I'd definitely recommend the MAC1 seal kit, and plan to use them on a few of the pellet guns I had as a kid that are just sitting in storage.

I also decided to try and pick up a few more models like the 78g. When S&W decided to get out of selling airguns they sold the patent and a bunch of parts to Daisy. Daisy produced the 780 (.22) and 790 (.177) starting in the early 80s, and eventually a chrome plated Model 41 in 1985. I found this 790 on Ebay and picked it up for a great price. The pics weren't so great, and the seller neglected to post a picture of the box that came with it. When it arrived, I opened the shipping box to to find a brand new pistol that appears to have never been shot!




Here are a couple pics for comparison sake between the 78g and 780. They're pretty similar, but Daisy opted for more plastic parts to include the rear sight and bolt.

 

[paul73]

When it arrived, I opened the shipping box to to find a brand new pistol that appears to have never been shot.

that is a rare luck indeed, great find.