I get 20 +1 with Taylor Freelance bases with standared followers. If I use Novak's followers, I can't get 21 but it makes loading 20 much easier.
On a side not, I bought a couple new gen. mags right after the ban. They eject much better. However, there was a transition period when they put #5 followers with these mags and I've run into jamming problems at the last two matches I shot (these also have Taylor Freelance basepads). I need to get a couple #6's and hope that helps.