I have an 870 Wingmaster in 20 Gauge that I would like to adapt for my wife and 12 yr old (small-framed) son to be able to shoot comfortably. Does anyone manufacture a stock with adjustable length of pull? I have seen the collapsable pistol-grip stock but have never used a pistol grip stock on a shotgun. Would it be comfortable for us for an afternoon? We shoot purely for recreational purposes (tossing claying birds out at the in-law's farm fields). Would it look too goofy shooting clays with the pistol grip? I know I could have the original stock modified for them, but I would like to be able to shoot it too. Something that could be adjusted to each shooter is what I'm looking for. I'd rather find a replacement stock instead of modifying the original. It's not a very valuable gun, I know. Any ideas ?