Interesting that NAC has the stocks. I don't need one and won't, barring a traffic accident with the gun in the back--I don't take my GL into the rough stuff. Too easy to fall and bang the chokes against a boulder, and I hear a dent on the threads causes a ton of grief which is only solved by a ton of $$$. So my GL does informal trap, duck blinds (NOT boats), and flatland phez. I got beaters for the rest.
Mine has the pistol grip BTW. It was a retirement gift from my brother, who gifted himself an "English grip" GL at the same time, but he knew I don't like straight grips. Killed a big cock phez with its first shot and has continued since 2006. I love it but use my RL 28 a lot more.