You will have to replace the ejector and use 9mm mags. The locking block is the same on the 23/26/27/32/33 and the barrel should lock up with the 23 block. Buy the 9mm ejector and remove the old one using pliers (after removing the trigger housing from the frame). Once the ejector is removed from the housing you can push the new part in by pressing the part into the housing against a hard surface. There is no other alteration necessary. FYI Glock has started making the 9mm standard with the 3 pin format instead of the prior 2 pin setup. Glock is big on standardization. The new 19 locking blocks are the 3 pin set up. -Coug