From the information i have from this forum, a guy got a Knoxx spec Ops adjustable recoil reducing stock for a 870 12gauge and used a adapter from Mesa Tactical and was able to mount it on a new youth small frame 20 gauge. Both items he bought from Cheaper than Dirt. The stock he said cost around 78 dollars and the Measa adapter was 17.00 dollars. The Mesa adapter was No. 93890 , so with this adapter i'm thinking you can mount just about any kind of adjustable stock that would fit the 12 ga. to the youth 870 with that Mesa adapter no. 93890. If you look down thru the forum under 20 gauge you will see a pict. and link on this information. its like on page 3 or 4 i think.. just keep looking under 20 gauge turkey gun.