Firearms and sound and recoil dampening

[hso]

If technology advanced far enough, how could we dampen the sound of a firearm low enough that it wouldnt damage hearing even when fired indoors without using subsonic rounds with supressors?

Suppressor.

 

[748]

If the building has enough room, sounds like a metro gun tube would be the ticket.

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I heave read that a metro barrel extension and a sub sonic slug has very light recoil and makes an amusing sound like a pop gun.

 

[George P]

If the building has enough room, sounds like a metro gun tube would be the ticket.

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I got to try one of them on a Beretta 390, you didn't need hearing protection and it swung nicely. Labeled from Hastings, it was actually made by Verney Carron