Any sound reduction with bloop tube, recessed muzzle?

[cr500]

I cant use a suppressor due to it being illegal here, but was wondering if there was any other way of reducing the noise to some extent? Will a bloop tube or 6-8" length of tube over the end of the muzzle quieten the muzzle report a bit? Will it have less of a crack when heard from a few hundred yards away?

[Artful]

If your in USA and put any device/addition on the weapon with objective of reducing the noise according to ATFE you are making a silencer/suppressor and subject to $200 tax and all legal requirements.

a Longer barrel will allow the gases to expand so lower the pressure impulse when the bullets exists the barrel. If you keep the bullets at 1000 fps or less there will be no crack involved. If you have access to any weapons with subsonic ammo available (22LR, 38 special, 44 special, 45 colt) you can hear what it would be like - visit a cowboy action shooting match and listen to older carbines in subsonic loadings.

[cr500]

No, I,m not in USA, but I,m not sure on how they would view a bloop tube. It might be a problem, not sure. I was wondering what the muzzle blast was like. I take it that with no sonic crack, it will still be quieter to people standing a distance off.
I was hoping that a longer barrel might make it quieter again, but if it doesnt make much difference, then I will go with a 20" barrel.