SMALL
Small will fit any stock with these dimensions including models shown below.
Stock Dimensions: 1-1/2” to 1-5/8” wide  X  4-3/4” to 4-7/8” long
Beretta: 391, Xtrema
Browning: BLR & A-Bolt models
Marlin: 336, 444, 1895, 450
Mossberg: 500 (Small size stocks including Youth, Bantam, Synthetic (pre-99), 9200/9300 models
New England Firearms: Pardner & Handi-Rifle
Remington: 870 Wingmaster, 870 police and Youth models, 1100 Semi-Auto, 700 ADL/BDL (Stock sizes of 4-7/8” or smaller. For larger stocks use medium.)
Ruger: M77 Mark II Synthetic (Pre-2001) (Post-2001 use medium), M77 Compact, Mini-14
Savage: 110 wood stock
Winchester: 1200, 1300, Super X2, 70 Classic, Carbine, Featherweight Models, 94 wood Stock
 
 
MEDIUM
Medium will fit any stock with these dimensions including models shown below.
Stock Dimensions: 1-1/2” to 1-3/4” wide  X  5” to 5-3/16” long
Beretta: 391 Synthetic
Benelli: Super Black Eagle & SBE II, Nova, M1, Montefeltro
(All above field models only)
Browning: BAR, Citori
Mossberg: 500 Synthetic (Post-99), 835, 935
Remington: 870 Synthetic (Post-99), 1187 Synthetic (Post-99), 700 ADL/BDL (Larger stock sizes), model 7
Ruger: No.1, M77, & 77 All Weather Synthetic (Post-2001), Red Label 12 & 20 ga.
Savage: 110 Synthetic Stocks
T/C: Encore, Omega Muzzleloader, Black Diamond
Winchester: 1400/1500 Semi-Auto, Super X1, Model 70 Black Shadow/Classic Stainless (Pre-99)