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block the gas vent in GB to simulate high(pressure) brass?


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That will do nothing... By the time the piston as reached that point, it has already relieved all of its pressure. It's just meant as a way of keeping the spent gasses from going all the way through the gas tube and into the receiver. If you perhaps want a slightly dirtier carrier, then block it... but it won't do diddly to increase pressure and make the shotgun cycle better.

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The vent is there to allow gas behind the piston to evacuate efficiently as the piston is driven back by expanding hot gas in front of the piston.

 

Blocking the vent, or welding it up, prevents gas behind the piston from exiting at the same rate as the gasses in front of the piston are expanding, trapping gas behind the piston, and requiring a hotter load to overcome the additional resistance and cycle the action.

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That would increase the amount of gas and pressure needed to cycle the action. The Russian engineers got it right.

Yup. The Russian Engineers usually did a pretty good job designing things, it was the communist workers who did not give a crap about what they made that caused the problems. Well that, and um.... the Vodka did not help either. haha.gif

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I think the best way to simulate a high brass load is to open up the gas ports. You will use more gas pushing on the piston and adding to recoil instead of pushing the lead out of the barrel.

 

 

That would increase the amount of gas and pressure needed to cycle the action. The Russian engineers got it right.

 

It would actually increase the volume of gas needed to build pressure, but take less pressure to move the larger piston (given the change in mass and friction are negligible) for an equal amount of force. Think of it as a truck with small tires versus big tires. The small tires fill faster, but the bigger tires can lose more pressure before they are flat.

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as bill nye would say, "SCIENCE!!!!" wasnt always my thing. i just figured thst there is gotha be another way to design this thing to work with american bird shot... was smokin clays with hand thrown clays today and its just so satisfying... gun was cycling everything ( after opening 3 of 4 up to #40 drill bit) but for the timid etc, it would be nice if there was another way....

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