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S&W 78G dilemma

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bpratl

bpratl

Member
Apr 19, 2017
33
1
MA, United States
After resealing my newly purchased S&W 78G I had a small leak from the poppet, so I will have to fabricate a peek replacement poppet.
I also noticed a gas leak from the bolt probe area and the bolt was very tight when opening.
I contributed this to a new tight probe O-ring, but I was wrong. I noticed the probe was not
centered in the barrel so after taking it apart again and making careful measurements I found
that the breech was warped .030" in the center. I believe that it was due to someone trying
to reseal it and did not realign the TP to the barrel and tightened up the breech so and It took a
set after sitting around for many years.
I decided to heat it up, with constant pressure, to relieve the stress and to my HORROR it snapped in half
cry.gif
.
I spent many hours aligning and tig welding it back together. Right now it looks good and is properly
aligned, but it is very disappointing to destroy this gem after only shooting 20 pellets through it.
Hopefully it will perform like it was designed. Time will tell. 
 
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I went with this poppet, it works great and should last a long long time. This seller had it to me a lot earlier than the auction said it would be. I have a lathe and a mill, but it wasn't worth it for me to buy the material and then machine it when I could replace it all for $24.

https://www.ebay.com/itm/Smith-Wesson-78G-79G-Daisy-780-790-HOT-Modern-Improved-Valve-Stem-Poppet-/372928190909?_trksid=p2349624.m46890.l49292
Click to expand...

That is the same guy that I bought my 78G from. He advertised it as having a small leak and said that he would re-seal it for $40 if I wanted. But I bought it as is because the price was really good. It’ll hold CO2 for about four months. So I’m not worrying about resealing it anytime soon. I was told by another gunsmith that those valves will give you about another 20 FPS. 
 
Upvote 0
I went with this poppet, it works great and should last a long long time. This seller had it to me a lot earlier than the auction said it would be. I have a lathe and a mill, but it wasn't worth it for me to buy the material and then machine it when I could replace it all for $24.

https://www.ebay.com/itm/Smith-Wesson-78G-79G-Daisy-780-790-HOT-Modern-Improved-Valve-Stem-Poppet-/372928190909?_trksid=p2349624.m46890.l49292
Click to expand...

I also have a lathe and mill but you are right, by the time I set it up and design and fabricate a new poppet

it is better to purchase one, which I did.
 
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