Thoughts on the old S&W 79G pistol

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  • john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Hi, we are cleaning out the mother-in-law's place and came across a S&W 79G CO2 air pistol. I'm guessing early 70's??

    No cylinders and we are in the city (so it's a good thing there are none!), so I don't know how it shoots.

    Any one with experience shooting them?
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Nobody?

    Seems like a pretty nice air gun. Oh well, will have to take some pictures and run a few down the pipe when I get back home and give a report.
     

    JoeRinMD

    Rifleman
    Jul 18, 2008
    2,014
    AA County
    John,

    I have Model 78G (the .22 caliber version of the same pistol) that I bought new in 1973 or '74. It was the very first gun I ever bought with my own money...earned from delivering the Washington Post on a paper route. I've always enjoyed shooting it, however it has never sealed very well. It's fine when it's being shot, but the CO2 leaks out if stored with a cylinder in the pistol. I've sent it out a couple of times to get it repaired, but it's always had this slight leak. In any case, it will never be sold. It was the first pistol that my son shot and one day it will be his.

    Joe
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    I finally got home and bought a box of CO2.

    1st cylinder, install... nothing. Oops, they go in "upside down". The nipple end is at the bottom. Flipped and SSSSSSSSSS! Major leak around the bottom cylinder nut.

    New O-ring from my collection.

    2nd cylinder, install and .... a few hisses then silence. Loaded a pellet, aimed and fired! yeah. Shot a bunch of random stuff in the back yard (14 acres) with good accuracy. After around 30 ish pellets .... SSSSSSS. Hmmmmm, that's not good! Maybe it has a low pressure release?

    3rd cylinder, install and SSSSSS from the body of the gun. Rats! Got a seal leak internal. Oh well, it was fun while it lasted. Now to get busy and re-seal it.
     

    JoeRinMD

    Rifleman
    Jul 18, 2008
    2,014
    AA County
    John,

    The first generation of the 78G/79G pistols have a power adjustment screw under the muzzle, as well as an adjustable trigger. They also have a way to release the remaining CO2 in the cylinder when it gets low....you pull back on the cocking lever. Do you have the owner's manual for the pistol? If not, I can scan mine.

    Joe
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    ^ I do not have a manual. The gun was in my deceased FIL's sock drawer for the last 20+ years... I would LOVE IT, if you would be so kind as to scan the manual! PM me if that's no trouble. (Thanks!!)

    Anyway, I took the gun down today with help from

    http://anotherairgunblog.blogspot.com/2009/02/smith-and-wesson-model-79g-disassembly_04.html

    There are a half dozen-ish articles on the 79/78G. Great pictures and tips. Also found Numrich has the schematic.

    I replaced all o-rings (except the small one in the cylinder bolt and the one the guy in the article made from 90D urethane. The job is pretty easy if you have a modicum of dexterity and a couple flat blade screwdrivers. The only tricky part is getting the top half back on as the cocking lever/spring wants to pop up. A bit of fuss'n & cuss'n and I figured out how to hold it so the top would slip on.

    Inserted a new cylinder and ..... it held pressure! Yippie. Back in business.
    After shooting 30-ish rounds, dinking about with the power screw and the sights I thought....Chrono!

    3 rounds 478, 479, 476
    shot 20ish more and it still sounded powerful so.... 3 more rounds
    480, 475, 479 ? Still?
    shot 10 more and ....WTF??
    489, 490, 492!
    shot 10 more and
    492, 492, 492 ??? Yes, 3 identical readings.
    shot 10 more
    488, 491, 487 (will it ever weaken?)
    shot 10 more
    478, 480, 473.

    It's sitting at my "range" now, but after over 100 rounds shot, it's still ripping across the chrono with undiminished fury! Oh, and did I mention that it's accurate as all get out? In 25-30ft ranges it's holding tight groups on a piece of 2x6 and popping a gatoraid bottle at will. When I tried to group, it put 3 rounds in a space of a penny at 25ft.

    So.... if you EVER find a 78G or 79G ---> snap it up. Especially if it "doesn't work" as you can get them running sweet with a 25 cent investment and under 20 minutes of time.
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Dag nabbit!

    Gun started hissing at me yesterday. The small seal in the cylinder nut blew out. Replaced that and burned through cylinder. Then it started hissing internally. :sad20:

    There was one seal in the transfer (I guess it's called that?) that holds pressure and is what fires the pellet. It's the one that the guy in the article manufactured. I took the gun apart and dug out the old blown seal and put in an o-ring. Well.... it sealed tight and the gun worked with shop air. BUT the o-ring held the moving parts from moving when under full CO2 pressure.

    I found some flat washers of nylon that might work from Fastenal. Will have to get them shipped in and try it.

    Guess i lost the bet with myself that those 2 seals would be OK! Yeah, shortcuts nearly always take longer for me.
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Well..... Have you ever both broken something and fixed it at the same time? I did that today. The nylon flat washers I ordered came in today, so I grabbed them and tried to insert them. When I tried to push out the pin, the brass housing snapped around where the washer goes :sad20:. Ruh-roh. Well, I put a washer on it anyway and assembled it. Tried it and it's holding pressure and in fact shooting hard.

    SmithandWesson_78G_schem.jpg


    The part I broke is #56. Naturally, out of stock. I do have a buddy with a lathe... if it fails to hold pressure, it will have to be customed up!

    If you need parts, Numrich has many of them in stock
     

    vafish

    Active Member
    Mar 13, 2012
    399
    Commonwealth of Virginia
    Those old smiths are somewhat collectible.

    I had one that I had bought as a kid and didn't use anymore. Listed it on the S&W forums for more than I could figure it was worth and it was sold in a few hours.
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Two years later and I finally found the parts to repair the airgun. Mac1 has reseal kits including part #56 along with all orings to seal it. Installed all parts and its back in busness.
    Kit delivered was 35ish. Shipping was quick too.

    Just thought an update was called for.
     

    jessebogan

    Active Member
    Feb 25, 2012
    503
    I have one and I love it. A joy to shoot. Remember to put a drop of "pell gun" oil on the tip of the cylinder. Helps keep it lubed up. It may have an adjustible trigger as well.
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    Tim McMurray (Mac-1) is an airgun guru. I have several of his customized airguns and had the good fortune to visit his shop in CA. If you run across an old Crosman in need, try Rick Willnecker in PA - Precision Pellet http://www.airgunshop.net/services.html. He's another airgun guru with a treasure chest of original Crosman parts.


    Thanks for the link, there are a couple in need.


    Update on functionality.

    Put the kit in and a new cylinder. No hiss. Loaded a pellet, pzing! Loaded a dozen more shooting at a mark on a box. Hitting it too ;). Put the gun down for 24 hours and THEN remembered to chrono it. 460-480 fps. After 50 shots it started to drift down to 440-450 fps. Stopped chronoing and just plinked a dozen shots.

    Next day, amazingly released the remaining pressure from the original cylinder.

    I'm happy.
     

    john_bud

    Ultimate Member
    Sep 23, 2009
    2,045
    You won't believe this (I nearly don't), but it's true...

    Took a picture of the pellet gun next to its new (to me) brother and the piercing deal felt stiff. On a hunch, I loaded a pellet and shot a hole in a layer of industrial cardboard.

    So, big deal...right?

    Yeah, except the gun has been sitting since September. Dang thing has pressure still holding after five months! The mac1 seal kit is amazing!
     

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