The PTR 91 KFM4 is configured with a 12.5-inch barrel and HK53-pattern handguard with vertical foregrip making it the most compact PTR 91 variant. As a short-barreled rifle under NFA it requires a Form 4 transfer or Form 1 to manufacture. The KFM4 designation references the HK G3KA4 short-barrel military configuration. Full-power 7.62x51mm from a 12.5-inch barrel produces a substantial muzzle blast. Type: Rifle Action: Semi-Automatic Caliber: 7.62x51mm NATO Capacity: 20 Year introduced: 2010, USA Weight: 176 oz Overall length: 33.5" Status: Active Intended use: tactical, collector