You guys that roll your own lead are killing me ;^) Not sure if you have actually played with Rowland brass yet, but the added length of the Rowland brass over standard might give some seating fits on the ogive of the bullet. Perhaps not.

One suggestion if you have not tried some different feed lip geometry magazines might be to do so. It would be dandy to keep the meplate like it is if you can. The older style Colt magazines do offer a bit of difference in the timing of the release of the base of the loaded round, so that might help with the feeding.

Craig