There’s been a number of very good books written on the topic of suppressors. Some cover the historical development and every know application of suppressors; others, are simple non-technical but very useful presentations of what is on the market. I won’t subject you to any of that detail; instead, I’ll use the cross-section of a SIG silencer to convey the important points.
A suppressor is a tube designed to contain high pressure high speed propellant gases. A suppressor uses a combination of volume and baffles to cool and reduce the pressure of these gases as they move through the suppressor tube. High-speed, high-pressure gases escaping at the muzzle create a loud ear damaging blast.
As you look at the image of the cross section, the first thing you’ll notice is a large space at the entry point. This space is designed to allow the muzzle blast to rapidly expand; thereby, reducing its pressure and temperature.
The next thing gases encounter is the blast baffle. Each one of these coned shaped objects is a baffle. The Blast baffle’s job is to absorb the initial impact of the muzzle blast; therefore, it needs to be the most robust baffle. That robustness is accomplished by the manufacturer’s selection of materials and thickness relative to the other baffles. In a riffle the blast baffle is subjected to as much as 50,000 p.s.i. It’s the blast baffle does the heavy lifting.
Once propellant gases get past the blast baffle they encounter another space allowing them to expand further reducing pressure and temperature. Gases then encounter a second baffle which continues to disturb and provide resistance to propellant gases. This process continues all the way through the suppressor, with the net effect being taking the muzzle blast from 50,000 p.s.i. to 20 p.s.i. in a span of 8-10 inches or so. The benefit is the prevention of hearing loss.