I got one of these inserts and tested it today through an old legal sawnoff breakopen 12G - it was probably fairly loud but wearing muffs I've no idea.
No aiming system just point it at things that I'd like to put a hole into and a 44 leaves a pretty big hole
As Toby says, it's good for shits and giggles, quieter than a shotgun shell out of the same gun and the only real surprise overall was that the recoil was guesstimated at about half that of a shotgun shell.
I expected much more of a kick
Range is pretty much point blank but a bit of fun for forty bucks so no complaints here
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