Apex Tactical Barrel S&W M&P M2.0 Compact 9mm Luger 4" 1 in 10" Twist 1/2"-28 Thread Stainless Steel This Apex Tactical Threaded Barrel is designed for the M&P M2.0 Compact model with a 4.00" factory barrel. The stainless steel barrel has a black Melonite finish and features a 1:10" twist rate that is designed to increase accuracy performance. The thread pattern is 1/2-28 and a thread protector is included. this barrel is a true drop-in and requires no fitting. Includes thread protector with o-ring installed.