Any competent shooter on the planet realizes the sound muffling capabilities of the 2 liter pop bottle, but actually doing anything with such knowledge is a direct violation of Federal Law and could earn a careless individual the direct attention of the fine folks at F-Troop.
We all know that those people would rather burn a family to death in the course of a 'search' for rubber washers, conduit, and normal everyday reloading supplies than appear in court.
As my grandfather used to tell me: "A word to the wise is sufficient."
Regards,
L
Your heads up is appreciated. Tom