Alpha Wolf barrels establish the benchmark for absolute accuracy and combat reliability. It is the pinnacle of what every other barrel manufacturer strives to be. Exact tolerances allow for a drop in installation. Designed for lead, plated, or jacketed ammunition. Converts .40 S&W and .357 Sig to 9mm. Heat treated to RC 40-42, then Salt Bath Nitride coated. Mfg: Lone Wolf Dist.