A ball mill should be able to get into just the collar area without going up into the cone. I just did something similar with some aluminum K baffles a friend made for me; he'd pre-drilled the collars just above the flat at 1/8" and I opened these holes out with a ball bit on a Dremel to about ...

Not sure if I'm interpreting the artwork correctly, but it seems your bleed hole in the collar goes well up into the cone, is that correct? If so, my understanding is that you're missing out on a fair bit of potential efficiency as the gas stream isn't being skimmed directly adjacent to the bullet p...

Oops, sorry, I misread the company name.

Certainly looks like silencer parts. Guess you'd have to ask them what their lawyer says about it.

I'm fairly certain they meet the technical definition. But they're plastic aren't they? At that thinness they'd melt before you got a half-dozen subsonic .22" shots off from a powderburner most likely. Not terribly threatening in terms of firearms use. Or maybe it's because AirArms is a UK-base...