The Apex Grade Semi Drop-In Barrel for the S&W M&P is available in either a 5.00'''' or 4.25'''' option. The stainless steel barrel features a 1:10'''' twist rate. The design increases accuracy performance, making the M&P capable of shooting as small as a 1-1/2 inch grouping at 25 yards. Accuracy test results based on using a mechanical rest. Final results may vary based on shooter ability, ammunition selection, and variations in factory firearm tolerances. Direct drop-in replacement of factory barrel. Improves accuracy and optimal performance is seen with bullet weights of 115 gr. Through 147gr. Using 9mm jacketed ammunition. Due to variations in factory slide tolerances, slight fitting ma Mfg: Apex Tactical Specialties Inc