Hi, excuse my ignorance. Glocks seem to be a very ‘Proctor-Silexy’ kind of weapon. Are the magazines interchangeable? In other words; excepting for length, would a G17 magazine fit any 9mm Glock? Is this true or not for other handguns? Would any 1911 magazine fit in any 1911 manufacturer’s product, assuming common caliber. Or are all magazines model and/or brand specific?