Why not? As I understand it the longer barrel increases accuracy mostly by giving you a longer sight radius and more weight to make the swing smoother. I know I will look silly but wouldn't a 20 inch barrel with one be better then without? Sure not as good as adding another six inches of real barrel, but better than not having it.
The barrel is cylinder bore but I am thinking about getting it threaded for Remington chokes.
There are many disadvantages when using a extremely short barrels for clay targets.
The main one being that you will not have complete combustion of your powder and will not achieve the intended velocity, meaning especially where trap and sporting clays are concerned your pellets will not have the same amount of energy and won't travel as far, you may also experience your pattern spreading out earlier than it should where long distances are concerned.
Sight radius, doesn't really effect shotguns like it does pistols or rifles, since once you mount the gun you shouldn't be looking at the barrel, remember you are pointing it not aiming it.
Short barrels don't have the mass of the longer guns, more weight equals less recoil, which is desirable if you want to do any amount of clay target shooting.
Also not having that weight out further away from you will make the gun whippy and more difficult to control, this would effect skeet especially but trap and sporting clays almost as much.
Short barrels ARE louder and not just because the sound is a little closer to you, no it's the unburnt powder burning outside of the barrel, that's what is making all the noise.
If you are out at a club participating, having fun and being safe and respectful of the others around you, then have at it, shoot whatever you want. But if you are disrupting the environment and you bring a "you're a bunch of old fudds what do you know" attitude with you, you aren't going to have a very welcoming experience.
Believe me most clubs in canada are filled with friendly, helpful shooters that want nothing more than to bring in MORE shooters!