Bosun, I have nothing against pistol gripped shotties. I kept my Persuader the same way for years.
I was making fun of the Barret style muzzle break. And yes that's a factory break and it's also available on the 930 semi-auto.
Another point of interest is that Mossberg is releasing all of the 590A1 variations for civilian sales later this year.
The differance between the 590 and the A1 version is that the A1 is equipped with a thicker barrel,steel trigger guard and safety. This is the version that is Military issue.