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Smith & Wesson 76 GBB


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i figured i should show this here since its been a while. This is one of my current projects, a gas blowback s&w76. So far its mostly done, but i need to get the has efficiency to be better on auto, and i need to have sling bars tig welded on.

Its a fairly even mix of machined and 3d printed parts. I mostly used 3d printing for parts that would be very complicated to machine (like the loading nozzle, the magwell, etc). this way if i wanted to make a second one, it wouldnt be nearly as hard as starting from scratch

 

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The only real issue im still ttying to iron out is the gas consumption. It is quite a gas hog, and on auto it cant quite get though a full magazine. it'll get like 40 shots before it cant quite reach the sear engagement again, and you can see the clouds of gas billowing out in the video if you fire more then a very short burst.

 

Im not really sure whats causing it, though my suspicion is that the valve delay is a bit too long, and its keeping the valve open even after the loading nozzle is no long aligned with the magazine. Unfortunately without fairly substantial changes to the receiver, or making an entirely new bolt, theres really no way to decrease the delay length further then i have already.

Both of those options are pretty time consuming so i havent gotten to try either yet. And thats assuming im correct about the problem. It could well be something i havent considered yet.

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16 hours ago, Brigg said:

Well, the release valve is in the magazine, i kinda dont want to mess with those.

Yes, I know. If you don't want to fiddle with the ones that work fine, maybe you could find some others, intended for CO2, maybe.

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