The knoxx stock does work. I owned 2 of them. 1 is still installed on a shotgun, the other has been retired.

While they do reduce the amount of recoil FELT in a shot, they do it by a series of springs which actually increase the recoil pulse, if you are use to shooting say your mossberg fast, switching over to this stock will more than likely slow you down since your timing will be off. This is what happened on my 870P. I went back to a plain jane speedfeed and could not be happier.

On your example I will also say stay away from any pistol grip stocks. A mossberg has a thumb safety on it, if you go a pistol grip style stock, you need to move a hand off the firearm to disengage it, OR just leave it off. Either in my book are bad choices.

Other things about knoxx stocks. They weight more. the grip protrudes from the firearm more and can get caught up on things in the tight areas of a house. There are alot of parts, IE more possibilites to break something. And yes the knoxx has broke, there were a few photos on shotgunworld forums about it.

I feel better with a speedfeed stock and forend (or even better the surefire equipped light forend). I have 5 870s, a Benelli M4 and a a M590A1. With the exception of 1 870, they all sport standard sport style stocks, even the benelli. Best thing I did to it. But this is a opnion related matter. If you like the PG style stocks, then go for it, I however did not.

Uploaded a before and after for you.
After- how I like them


Before