This Mossberg manufactured late veriation pistol grip walnut stock with cheek rest and spare magazine storage compartment is for the model 42MB(a) bolt action rimfire rifle which uses the slightly shorter trigger guard with a round end at the bottom and is in very good condition except for a large chip at the bottom and light dings with handling marks. The late variation stock is designed for the S100 or S130 receiver peep sight.  (file photos)