I heard a rumor that Mesa Tactical is going to be coming out with an adapter in the near future that will allow large-frame 870 stocks to be installed on small-frame receivers. If true, this might give you some more options if you just can't find the 20ga stocks.
Thanks for the heads up. After posting I googled & looked at the products they have. Very interesting.
The real reason I am posting now is to say I ended up buying them on ebay. Paid more than the original price, both new, one in package & one not.
I have two Remington 7600 Pumps I am converting to tactical / old man guns.
One is a 270 Win. I will cutting the barrel down to 16-1/2" with the Knoxx stock. I will have a scope rail with a VXII 3x9x40 Leupold. This is such a flat shooter that I never have a problem hitting what I point at to 300 yards.
The other one, Remington 7600 in 308 Win. This is my gun when I can no longer tote my Springfield M1a Bush Rifle. This rifle will sport the same length barrel as the M1a, 18.5". With the Knoxx SpecOp stock I will still be able to use a rifle of Nato caliber. This rifle is a copy of the police version that Remington has in both .223 & 308 with the Knoxx stock on them.
Both guns will be "parked". I will be able to carry these rifles & with a pocket full of 4 rounds clips or a couple 10 rounds would give me plenty of fun plinking. The Knoxx would not only absorb most of the recoil but would be adaptable for length of pull & make this a very easy to maneuver in tight situations.