Silencers, how they are made

Question
Are silencers made to last indefinitely, or do they incorporate baffling materials that wear out?

Answer
Hello Johnny,

 This is a little outside of my area, but I may be able to shed some light on your question anyway.
All silencers are not exactly the same, but the basic principle will be similar. They incorporate "chambers" that the bullet will pass through, and each one of the chambers will have some baffling material to "absorb" some of the sound associated with the cartridge firing.
The chambers will usually have some material to "catch" the sound as it enters the chamber, and will trap a bit of it as it passes through each chamber. (Consider this to be similar to the insulation in a house. The idea is that the insulating material creates many tiny air chambers that insulate both heat, as well as sound). This baffling material will also trap some of the other stuff that is passing through the chambers such as smoke, and other tiny particles of airborne debris such as lead, or powder residue.
The residue that these contaminates leave behind will tend to clog up the air "chambers" that the baffling material creates, reducing the efficiency of the baffle. Sometimes it can be cleaned, but in the silencers that I am familiar with, it is intended to be replaced with new material.

I hope this has helped answer your question.

Brad