Is there any silencer for double barrel shot gun?

Answer 1

You would need a suppressor for each barrel.

Shotgun silencers are notoriously ineffective because of the wadding. Regular silencers have a series of baffles that the bullet passes through that scoop away hot, high pressure gas every time the bullet goes through one. The bullet will often pass through 3-10 of these baffles before it leaves, so a lot of gas is scooped away.

A shotgun has a wadding which would get caught in the baffles on the first shot, rendering the silencer useless or at least dangerous.

The solution has been to use a tube with lots of holes in it that allows gas to escape but keeps the wadding together until it's out the end of the silencer. Holes don't allow as much gas to be diverted away, so more remains as the bullet leaves the suppressor, and the gun remain pretty loud.

The other problem with a shotgun silencer is that, as with any large-bore suppressor, there is a really big hole for gas to escape from, so it is hard to divert the center of the gas stream away. .45 silencers are substantially louder than 9mm silencers, which are louder than .22 silencers.

A slug-firing shotgun could be suppressed, but again the hole is quite large. In addition, most slugs leave the barrel over the speed of sound, so the sonic crack would defeat your goals with the silencer. If you used a sub-sonic slug you might get a moderate degree of satisfaction from a shotgun silencer. If you did all this in .410 it might even be decent -- but at that point you may as well get one for your .40 cal pistol.