Sunday, February 8, 2009

Resealing the Smith and Wesson Model 79G, Part 2

And on I go.

The small o-ring for the piercing assembly was replaced with a Viton o-ring.

As was the large one. I didn't get an exact size match but I couldn't tell if the old seal was stretched out...a 114 might be better?

The new piercing pin seal goes in.

As the nut is screwed on. The rest of the piercing assembly was put back together in reverse of disassembly.

That tiny brass screen goes in the hole in the grip frame.

The valve attached back to the frame with the three screws.

The trasnfer port gizmo is in place. Note that this is a metal to metal seal from the valve to the barrel. I noticed one of the sellers of aftermarket seals provides an o-ring for this...

The safety components.

Put back in place and the trigger pin is driven in. You can tell the correct side to start as you'll see fine ridges from the knurled end of the pin inside the hole.

I shoehorned in the spring from the top, if I were doing it again I'd put it in place and then install the trigger...it was a bit of an ordeal.

The barrel in place. It's a good idea to test and see if it's lined up correctly.

The hammer spring and guide are put back in. I found that I had to hold down the trigger to get the hammer back in place and put the slide back on top. I did everything in reverse of disassembly at this point. No real surprises cropped up.

The adjuster rod, guide and adjuster screw assembly were replaced. The rear sight was replaced as well.

Three days later and it's still holding CO2! I'm getting about 427 fps on the high power setting and 402 on the low power setting with a fresh cartridge (7.9 gr. CPLs), I'll chrony it again in a week to see.

6 comments:

wildturk said...

Excellent post! I had no idea what size O rings to get for my SW model 79G until I found your blog entry. THANKS!

dhemb said...

I'm working on resealing my 79G. Upon re-assembly I noticed an alignment problem with the barrel. The barrel will not lay into the portion part of the upper casting where the top set screw is. There looks like about 0.080" between the barrel and this "cradle". Could the upper casting have been bent? I had no difficulties disassembling the gun (this time) and have shot it since the last time I did. I'm befuddled.

dhemb said...

I'm working on resealing my 79G. Upon re-assembly I noticed an alignment problem with the barrel. The barrel will not lay into the portion part of the upper casting where the top set screw is. There looks like about 0.080" between the barrel and this "cradle". Could the upper casting have been bent? I had no difficulties disassembling the gun (this time) and have shot it since the last time I did. I'm befuddled.

Anonymous said...

Thank you for the great info on the piecing unit. Just received my orings from Grainger. Had the 780 fixed in 15 minutes. Wow , glad to have her back online. Thank you!!

Guy LoMonaco said...

Valve is not holding. All air is leaking from top. Is there any way of sealing it? It looks like a solid unit with the rear pressed into place at manufacturer

Felice Luftschein said...

Read all of the articles in the series, starting with disassembly. It is resealable.