Wet suppressors
It's a long time tradition to reduce the sound signature of a .22 rimfire suppressor by using a liquid or gel inside it to absorb more heat in the initial shots, and thereby reduce the 1st round pop.
There are OSS stories of field operatives using aftershave in their High Standard HD suppressor guns.
It's a pain in the patookus to disassemble the apparatus, and the gel to the baffles outside of the bullet path, and reassemble it. And with a lot of gels, they smoke like a chimney the first few rounds.
Well ran out this AM, ran a couple hundred through 2 suppressors, and believe I noticed a much reduced sound signature on the 1st round, The automotive white lithium grease seemed to last longer, and did not get runny when left in the suppressor overnight. Yes, it smoked a lot.
Probably not something I'll do all the time, but I have no doubt I'll be doing it more.