@CaptainFuggetaboutit @_Seraphim_ @matty @PatrickCooper Here's an illustration of how seriously the ATF pole smokers take sound suppression. This is the muzzle device from a Colt XM177E1 carbine, which came with either a 10" or 11.5" barrel. The gas port is in the front sight assembly as seen on M-16s, etc. and there wasn't enough backpressure for the bolt to consistently cycle. So, Colt developed a muzzle device that trapped gas long enough for the weapon to cycle consistently. It was as loud as a 20" M-16. The military used them, whee. In the 70s, some ended up on the commercial market. The ATF tested them and found that, while the carbine was as loud as an M-16, without a muzzle device on, they were even louder. The sound signature was reduced by about 2 db, therefore they were restricted NFA devices. This is still the case. It wasn't because they used teeny tiny baffles - there were plenty of suppressors in the old days that didn't have baffles, but consisted of a barrel or tube drilled with ports, wrapped in various materials to slow the gases, then enclosed with a tube. NFA item. No baffles. It's because any device that reduces the sound signature AT ALL is a considered a suppressor

There is an entire industry for retro guns, and the guys who make these will usually send them in to the ATF to get tested so that they can show that it's not an NFA device... because it doesn't reduce the sound signature