Marlin- 1993 JM Stamped 336W Barrel: Micro-Groove Rifling with a 20" barrel Marlin's proprietary Micro-Groove rifling (introduced in 1956). it utilizes a higher number of shallow grooves. This enhances gas sealing and accuracy while drastically minimizing bore fouling Caliber: 30-30 Win Capacity: 6+1 Genuine "JM" Stamping: Because it was produced in 1993, the barrel features the highly sought-after "JM" proof mark inside an oval. This denotes original Marlin craftsmanship before the Remington acquisition. Crossbolt Safety (CBS): Introduced to the 336 lineup in the mid-1980s, the 1993 model features the traditional push-button crossbolt safety located at the rear of the receiver. This blocks the hammer from hitting the two-piece firing pin Hardwood Stock: Birchwood synthetic