This is a “weld in” part so it will be supplied without Parkerizing. We have stretched these mag wells to fit our biggest Zmag. There is a known issue with Zmags “growing” with each run of mags manufactured by Schockwave Technologies. Due to this variance in Zmag specs we can only say the mag wells fit our Zmags, but will not guarantee they will fit your Zmags. Any problems with Zmags fitting your mag well should be taken up with Schockwave Technologies.