And you're able to load 13 rounds without any FTF? What kind of mag springs are you using. I think I'm running the same setup as you yet I'm having frequent FTF if I load more than 10 rounds. Are you using Clark's conversion kit?
I have also converted a 2011 to 460 Rowland. However, I have been having FTF problems with mine even though I am using double magazine springs. Are you able to load 14 rounds onto your magazine?