These are the same 9mm barrels we use in our 9mm conversions. Starting life as a raw 9mm 1/10 twist blank, we machine them in our shop for maximum concentricity, accuracy and include the special hand polished feed cone we have developed to ensure smooth feeding. Barrels are finished with a black nitride coating for extended durability. Muzzle is threaded 1/2 x 28. I HIGHLY recommend purchasing our deadblow buffer in conjunction with our barrels. It reduces felt recoil and stops bolt bounce.
NOTE: the guaranteed to feed barrel guarantee does not apply to 9mm Glock lowers made by Spikes Tactical. They have an inherent design flaw that prevents them from feeding heavier longer HP ammo such as Federal 147 HST. We are working on a solution, but this is a known issue directly related to the lower, so buyers should be aware before making a purchase.