Ever Wondered how gun suppressors work?

In almost every action movie, one common thing we see is the protagonist or the guy who wants to kill the protagonist screwing on a barrel to the end of the gun as a part of their final preparation for the duel. Once the shooting starts all that's heard is "pew pew!" and spectators carry on as nothing happened. Well, that's not the case, and in real the suppressor only makes a BANG! into a bang! 

Making a gunshot that's close to 160 dB silent is not really possible. Guns are loud in three different ways. The first significant sound is made by the hammer of the gun hits the firing pit. This is nowhere close to how loud the actual gunshot is, but it's still a sound nonetheless. The hammer is the small moving piece at the top end of the gun that makes the metallic clicking sound. This hammer striking the firing pit causes the gun powder in the shell to ignite and explode. The explosion makes the gunpowder into gas, pressurised gas close to 3000psi. This pressurised gas propels the bullet and the gas exiting the gun along with the bullet is what makes the BANG sound. It's comparable to the pop of opening a champagne bottle. This is where suppressors do their part. 

Suppressors are essentially a metal tube made of aluminium or titanium and consists of many chambers in them. Along with that, the suppressor also has a larger volume when compared to the barrel of the gun. This enormous volume and the chambers together help by giving room for the high-pressure gas to expand and lose pressure. The pressure drops down to 60psi. Lesser the pressure, the lesser the sound. So now with the suppressor on the sound is down to 20dB. 

The last sound is the sound made by the bullet because of the speed it's travelling and a suppressor doesn't help here. Just like how planes when they reach the supersonic threshold and create a sonic boom, bullets also make "ballistic crack" when they reach a speed of 1100 ft/s. The only way to control this sound is by using ammunition that has bullets that travel at speeds lesser than the threshold. 

After controlling these three sounds, the gunshot would be significantly more silent, with just a small pop and the sound of the bullet whizzing through the air for which nothing can be done.

So you can never be completely unnoticed while firing a bullet from the gun.