I've got two magazines with Arrendondo bottoms and extremely modified followers that will hold 20. But, and it is a big but, they are not reliable. Saturday at the Gator I started one stage with one, and encountered a type of malfunction (FTF) that I never had before. The round that failed to feed was almost stright up and down, and teh sides of the case were generally paralell to the sides of the mag. I've tried Wolff springs and ISMI springs and even Arrendondo followers, and have problems when loading over 18. I have Dawson bases with moderately modified followers and ISMI springs which although they will only (I never thought I would refer to "only" holding 18) hold 18, function flawlessly. After taking about 10 seconds to get that malfunction cleared, I went with Dawson bases and 18 rounds for the rest of the match and never had a malfunction. I was still pretty slow, but not because of the magazines.