Where is a good source of info for AR15 buffer and buffer springs in regard to 9mm blowback, No Gas. I hav 2 lowers, 1 uses Glock mags and never hiccups. Other uses Colt mags, bcg will come back far enough to eject and pick up new round but will not recock fcg. I am planning on cutting 2 coils off buffer spring till it runs reliably. Have taken buffer and spring and changed them out with same results. Is there any diff in regard to bcg travel with Glock vs Colt style mags? Thanks