The MK1 MOD 1-M line revamped for 2018 features the PWS long stroke piston system. Internally this line offers the tried and true system that PWS owners have grown to know and love. Featuring a free-float MLOK handguard forward assist controls and a more true to mil-spec design the MK1 MOD 1-M line is a go-to for not only civilians but also Law Enforcement. With the fully forged upper and lower receivers the MK1 MOD 1-M is a no-nonsense tool for when you need a high value option that is relentless and unstoppable. - What PWS-aficionado