my brother has a degenerative neuromuscular disorder called c.m.t. in the past 2 years he has became wheelchair bound and his arms and hands have lost a lot of motor skills. We've thought of outfitting the 1100 with tactical gear, but have only found such equipment for the 870 (pistol grips, collapsable adjustable stock, picitiny rails all over it, etc.). are they pretty much universal?