Tuesday, October 16, 2012

Another S&W 78G

A friend made me a good deal (I fixed several of his computers for him as a favor a while back) on a S&W 78G he picked up at a gun show.
The box.
Side. From the Bangor Punta era.
All the documentation was there.
Not the original powerlets, but the original pellets.
Relatively unoxidized.
The pistol has some paint issues on the “slide”.
The grips also have a white coating.
Vintage powerlets with the bottle cap.
Paint problems.
I used a magnet to remove the power adjuster rod. Unlike the previous one I worked on, the sleeve did not slide out. Darn.
So I took some stainless steel tubing I had laying around and countersunk one end.
Fitted a long screw and trimmed the head undersize.
Added some slots.
An internal wrench of sorts. I held the tube with pliers and turned the nut to grip.
Held the end in a vise and gently whacked the slide with a soft face hammer.
And the tube came out.
Pile of pistol parts.
I discovered that the piercing pin was sheared off.
Only way to grip the pin was in a 5C collet as the large end would have fouled against standard chuck jaws.
Made it pointier without reducing any of the remaining length.
And it pierces fine.
I have one useful tip – holding the trigger down with a zip tie makes reassembly much easier.
I did run into some difficulty though, the pistol had no power. I tried a number of different solutions, lighter valve spring, lubing the hammer, triple checking that the transfer port on the barrel was aligned, replacing all o-rings (I had already replaced the dead original o-rings), etc. Then while reviewing my previous article I realized that I had made the seals from 80 durometer polyurethane rubber instead of the 95 durometer I had used the first time I resealed one…so a new valve seal was made and the pistol functions perfectly. Amazing what a change in hardness makes. I can now disassemble and reassemble this pistol blindfolded.

I’m probably going to clean up the slide and repaint and I’m thinking of making a .20 cal barrel for it as well. Given how long I’ve been taking between posts* we’ll see when that gets done…

*kids & work get in the way these days…


derrick38 said...

My S&W 78G also had that white residue on the grips. A soft nylon brush (no, not Felice's toothbrush) and some Pledge spray wax made it all go away and the grips looked like new.

Anonymous said...

Thanks for the great pictures, was able to reseal a leaker.

Anonymous said...

Great job...you are the man! Ray Carr

clefevre767 said...

Having difficulty getting the adjusting rod sleeve to come out. Have removed the small screw on the back of the slide. The slide did pop up but not by much. It seems to be caught on something and will not come off the frame. Is the adjusting rod sleeve impeding the removal of the slide? I have reinstalled the small screw at he back of the slide to reattempt removal of the adjusting rod sleeve but no go. Any suggestions? Do not have a lathe so unable to replicate the previous poster's tool puller.

Unknown said...

Great post. This will give me a good idea on how to rebuild my 79g

Unknown said...

Thank you.

I found my fathers g78 a few days ago... It was lying in a "wet" bag for at least 25 years...

It has some light dsmage in the upper slide and its paint is in a real bad condition.

Which paint did Smith and Weapon used to paint and can i get some of it today for repainting it?