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Discussion Starter · #1 ·
My new RFB fed and locked back with the gas adjustment all the way forward and in fact with it removed.

So the rifle appears to be ‘over gassed’ on any setting with a regular piston.

I wanted to use my suppressor on it so obviously I figured I should order the suppressor piston, which I did.

The suppressor piston appears identical in terms of the number of circular ribs and their placement and diameter. The only difference I can see is that the shaft of the suppressor piston is the same diameter all the way to the tip, whereas the regular piston is thinner on the shaft and only the tip expands to full diameter. I will try to post a picture.

I was curious as to how all this works, because it appears that the gas-port hits in the middle of the shaft, so some gas will go forward and exit the front of the rifle by going along the shaft, whereas the other gas would head towards the rear of the rifle, impacting all the circular plates on the piston, and make the piston hit the operating rod.

I was trying to visualize why the thicker shaft on the ‘suppressor piston’ would change the amount of gas flowing each direction, and also decided to look at how the gas adjustment would affect all of this.

Low and behold, there is no opening towards the front of the gun where the narrow piece of the gas piston goes. It looks like there might be supposed to be a small opening, but there is none. Again, I will try to post a picture.

Additionally, when I look at the adjustment nut, I realized it screws on and off the threaded portion of what I would call the piston cylinder, but that’s really all it does. It is simply an elongated nut with holes in the side to help you stick a cartridge tip in it to turn it. It doesn’t impinge on anything, or adjust a collet, or increase or decrease any distance of significance that I can see. The only thing it really does is push in an out the detent rod, so the only way it could affect anything in terms of gas flow, particularly since there is no hole in the front of the cylinder, is if that detent rod is actually affecting gas flow internally. I don’t see any way that that’s happening when I look at the design.

So....is there supposed to be a hole in the front of the ‘cylinder’...? If not, where does excess gas go, and HOW in either case does the adjustment-nut manage to change ANYTHING...???
 

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My new RFB fed and locked back with the gas adjustment all the way forward and in fact with it removed.

So the rifle appears to be ‘over gassed’ on any setting with a regular piston.

I wanted to use my suppressor on it so obviously I figured I should order the suppressor piston, which I did.

The suppressor piston appears identical in terms of the number of circular ribs and their placement and diameter. The only difference I can see is that the shaft of the suppressor piston is the same diameter all the way to the tip, whereas the regular piston is thinner on the shaft and only the tip expands to full diameter. I will try to post a picture.

I was curious as to how all this works, because it appears that the gas-port hits in the middle of the shaft, so some gas will go forward and exit the front of the rifle by going along the shaft, whereas the other gas would head towards the rear of the rifle, impacting all the circular plates on the piston, and make the piston hit the operating rod.

I was trying to visualize why the thicker shaft on the ‘suppressor piston’ would change the amount of gas flowing each direction, and also decided to look at how the gas adjustment would affect all of this.

Low and behold, there is no opening towards the front of the gun where the narrow piece of the gas piston goes. It looks like there might be supposed to be a small opening, but there is none. Again, I will try to post a picture.

Additionally, when I look at the adjustment nut, I realized it screws on and off the threaded portion of what I would call the piston cylinder, but that’s really all it does. It is simply an elongated nut with holes in the side to help you stick a cartridge tip in it to turn it. It doesn’t impinge on anything, or adjust a collet, or increase or decrease any distance of significance that I can see. The only thing it really does is push in an out the detent rod, so the only way it could affect anything in terms of gas flow, particularly since there is no hole in the front of the cylinder, is if that detent rod is actually affecting gas flow internally. I don’t see any way that that’s happening when I look at the design.

So....is there supposed to be a hole in the front of the ‘cylinder’...? If not, where does excess gas go, and HOW in either case does the adjustment-nut manage to change ANYTHING...???
My gas cylinder looks like yours. At 5 o'clock where it faces the barrel there is a small slot cut in it. So the more the nut is screwed down the more of the slot is covered, and more gas goes to the piston. Since the slot faces the barrel its hard to see. Hope that helps
 

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There was a good discussion on here awhile ago.
I have pasted a link.

Your "standard piston looks like my suppressor piston.
Are you using a suppressor now to shoot?
My RFB shoots great supersonic, unsuppressed at about 14.
I have to take the adjustment completely off to work supersonic with a suppressor, and that is hit and miss.
It will not cycle at all with any subsonic ammo.
Read through the link and see if that helps.
 
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