After posting the reply above, I went out to the shop & grabbed one of the Jefferson Outdoors DBMs for use with CZ527 mags, then dug out the spare CZ mag I'd bought after reading about this DBM. Swapped out the DIP DBM for the new Jefferson CZ bottom metal in the Mini chambered for 22 Grinch, and after removing the striker assembly from the Mini's bolt, ran a trial with 5rds of Grinch FF ammo loaded with Hornady 75 AMax bullets - they fed out of that 527 mag perfectly, much smoother than when running them out of the Howa poly mags in the DIP DBM. Great! - now all I have to do is find a few more of the 527 mags, and I'm all set. Not only does the 527 mag solve the feeding issue I was having, but it slips into the Jefferson DBM and latches just as easily & slick as it feeds rounds! Hokie-Pokie Kid, you rock!