HELP with 1377

[1377x]

I love this idea, but one question for you:
I assume that after cutting it the "flat" side would face down and the rounded surface up? Or maybe it doesn't make a difference?

its usually flat on all sides, a stock crosman transfer port gasket is square-no round sides like a regular o-ring, once youre in the line take your time
if you do mess up and end up with a wavy cut put that side down the straight side will go into the barrel

[Tater]

Thank you sir.