So even though I've owned cans for a while now, I still don't know enough about the different manufacturing methods to figure out the clean/don't clean thing. My Liberty Cosmic is "kinda clean it if you want to". My Rex Silentium is "Don't clean it". I think my Sig says "self-cleaning".
I was just watching the Shadow Systems video on their new can and they specifically said they manufactured it so the user can't clean the baffles.
I'm guessing a lot of it has to do with the various manufacturing methods and materials, but it's incredibly confusing.
*Very Roughly*:
Rifle cans don't normally need to be cleaned, and most can't really be cleaned (They are often welded shut). The gas of a rifle cartridge is generally hot enough and moving fast enough that while it lays carbon down, not that much, and successive shots will knock the carbon out.
Pistol Cans often need to be cleaned for the same reason, or rather that the gasses aren't moving fast enough to knock the carbon out so you get build up over time and have to do something about it. Pistol can's normally can be disassembled for this reason.
.22 and rimfire cans are the worst about getting dirty because in addition to the low pressure not self cleaning, rimfire bullets are often unjacketed so you get lead and carbon build up. IME .22 cans need to be cleaned the most frequently and as far as I know all commercially produced rimfire cans are made to be disassembled.
Ultrasonic baths work well as long as there is NO ALUMINIUM pars in them. For example my Rugged Occulus .22 can has an aluminium outer tube and titatinum (I think) baffles. THe instructions say to throw the baffles in an US, but not the tube. US cleaners will eat softer metals like that.
^^^All that is for "Traditional" baffled and monocore cans. THe newer 3D printed cans have way more complicated insides and the community is still seeing how they work. As mentioned, my Flow556 says to soak it in CLP then shoot the carbon out. I'm not sure what other makers with the flow through designs and smaller ports are saying.