I have come across imperfections in that area during the 1st pass of the boring bar, when I'm 3K-ing them. They say "paint hides a multitude of sins"... true to this point: They can't hide from HPA.Your post is going to solve a lot of mysteries, as time goes on.As to them being "tinkerer's guns"... I happen to like that fact, a bunch. In the mid '80s, when there was a real surge in aftermarket Harley parts here, we had a saying at my MC shop: "It takes more than a credit card, and a Crescent wrench, to build a real custom." With these, if a guy's gun works nice and slick... he probably either knows what he's doing... or is learning quickly.
My marks looked like that, except the area between was shaved down as well.... I can't tell the depth from the photo, but I managed to mostly polish mine out with some 220 grit paper on the end of a wooden dowel in a portable drill.... It wasn't perfect, but I figured the O-ring had a chance of sealing....I am confused, though.... where are your threads in the receiver, and what is the hole at 12 o-clock near the end of the receiver?....Bob
Are you sure you just can't shoot it?Even if it loses a 100psi a day, you can unhook your tank and not worry about it.