Do suppressors cause a loss of performance?

Saw the above video on The Firearm Blog today and I decided the how and why needed to be explained (in basic form). Do suppressors cause a loss of velocity and thus performance? Not really, at least not the ones you attach to the end of the barrel. An integral suppressor with lots of holes in the barrel or a shorter than normal barrel inside the suppressor body itself, perhaps.

Suppressors contain the expansion of gas inside a canister, keeping the hot gases inside by means of baffles, wipes, and magic. Once the gases have cooled and slowed down, they can then trickle out the muzzle quietly instead of exploding behind the bullet and creating the characteristic gunshot. Sorta like farting into a couch cushion. So the gas that propels the bullet at 12 parsecs to reach its supersonic velocity pushes and pushes normally until it reaches the suppressor, where, instead of going “bang,” it expands into the open space and puffs out, while the bullet is still tooling along.

Credit: DrNoob

In short, the full length of the barrel is used to propel the bullet as normal. It’s only until the muzzle (where you screwed the suppressor on instead of your flash hider) where things are different. So by the time the suppressor starts working, the bullet is going full speed already and the expansion of gas and consequent loss of pressure can’t affect its velocity.

Here’s an easy analogy using a garden hose. Does a sprinkler head with all its little holes cause a loss in water pressure? Nope. The water hits the jet holes with the same force as the faucet end as if the nozzle was uncapped.

Now take one of those special garden watering hoses with the holes all along the length. If the holes are of uniform size and spacing, the water pressure at the end of the hose will be less than at the beginning because it is being bled off. The last example is how an integral suppressor (one where the barrel has holes in it) bleeds off combustion gas to slow the bullet below supersonic. It can be done other ways, but we’re keeping it simple.

In conclusion, all a suppressor is doing on a rifle is catching the gasses at the end, not slowing down the bullet by robbing it of its “gas.” Since the bullet is still supersonic, that’s why subsonic ammo is recommended to further reduce the sonic signature of the gun, however, subsonic ammo develops less pressure, less velocity, and rifle performance is degraded. Not much of a problem with submachine guns or pistols where silence is often the primary concern.