This is a Ruger 77/22, or 77/17 stock. The stock can be used with the .22 LR, and .22 Magnum and can also be used with the .17HM2, or the .17 HMR. It's as easy as switching out the bottom metal and magazine.
The stock is a Boyd's Ross thumbhole. It is a pepper laminate that has the the factory polyurethane finish. It has a .920 barrel channel, and has a front Volquartsen pillar installed.
Very nice stock, and is in perfect condition.