Caliber: .308 Win – Action: Delayed Blowback Roller-Lock System – Overall length: 23 1/2 – Weight: 7.8 lb – Barrel: 8 1/8 match grade bull barrel – Magazine: 20rd – Stock: machined butt cap drilled and tapped for AR15 tube adapter – 5/8×24 flash hider H&K navy type polymer trigger group MP5 wide polymer handguard machined butt cap welded scope rail sling swivel paddle magazine release As of 11/1/15 51P PDW R’s will come with 5/8×24 barrel threading