Either get a real 12 ga. or buy the best computer speakers you can find and crank it up.
But none of this fake gun stuff, extremely dangerous.
[video=youtube;yPkr1XQFNJA]https://www.youtube.com/watch?v=yPkr1XQFNJA[/video]
Mmmh an efficient guard dog will not bark at an imminent threat, a low growl deep in the throat, yes. I guess it depends on the character of the dog, but in my experience, dogs protecting a propety ( real dogs that is, not rat size dogs or company dogs ) will bark at other dogs/animals, they will also bark if they are locked up/tied up...... but they will not bark if they think someone is climbing over the wall.....why ruin the potential fun !!
As for a fake gun..... why not ? I have never actually shot anyone with my real guns...... in fact i probably shoot them only twice a year in my conuco, mainly to make sure they go bang when I pull the trigger ( a gun is a tool for me, not an object of adoration ), and has the side effect of letting the-few-people around that we have guns.
One of my BIL actually ran off a couple of guys with a fake shotgun we left him ( he was keeping an eye on the house from next door ) and they fell over each other trying to get away...... that said i prefer not to have to pull the fake gun stunt.