Just my 2-cents. I bought one and frankly it was junk. Getting it to load, and actually feed, more than 14 or 15 rounds was really almost impossible - pretty shoddy construction, imo. There are 2 different springs in it, coz it's actually a 10-rounder with the base taken off and a bottom half married to it. I eventually gave up & took the plastic bottom extension piece off, made a base-plate for the top part (which is a usual 10 round mag.) and I just use it as a 2nd 10-rounder now. Works just fine, incidentally.