Holsters for Glock 21SF with Picatinny rail

Having a hard time finding a holster for a Glock 21 SF with the Picatinny rail. The Serpa I have I had to modify because the P-rail is thicker than the Glock rail. I have a Galco but its REAL tight even after Ive left my G21SF in it for 3 weeks straight now. I like my Serpa but Im wondering if Ill need something different for the few training classes and Im starting Prod Class in USPSA this coming 2010 season. Not entirely sure the Serpa is the best choice for USPSA/Training Classes

So anyone have any ideas?

Post up if you find anything. Raven didn’t have anything the last time I checked (early '09), and I picked up an Eagle G-Code holster at a gun show hoping that might work, but no dice.

Center of Mass holsters sells a G21SF-specific holster (kydex) that will accomodate a picatinny rail.