Reply To: Fx Impact Mods for more FPS / FPE

Forums PCP Airguns Fx Impact Mods for more FPS / FPE Reply To: Fx Impact Mods for more FPS / FPE

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JP003, When "flaring" the opening think of how a carburetor's Venturi works.  What is key is air will increase velocity as it is necked down, as is the principles of the Venturi.  So you are in essence making a Venturi in the brass transfer port that matches the port in the rear block.  Another thing that helps the flow is to not let air make a square 90° turn.  Break the edges down at the turn so it looks like it will "flow" into the barrel smoothly.  The end goal of porting is to make the air move through the valve housing, into the block, and through the brass transfer port as smoothly as possible, without air having to make sharp bends and pass over "ledges" where the ports don't match up; in effect, one smooth transition from the valve housing into the barrel.