It's every shell with the RCBS, but i suspect if you were to have problems with feeding, it would only be the 3.5" shells to cause problems. The mec can be adjusted for shorter shells and they even sell shellholders that take up the space so you can just use those without having to fool with adjustments.
My personal single stage press preference is my sizemaster which is the first version with all steel dies and brass crimp starters. Other than the excellent collet sizer i also have the universal charge bar which will give me any powder and shot charge i need with out having to fool around with bushings that give me what they want.
Mine of course won't load anything over 3" but i very seldom load anything over 2.75" anymore. 3.5" shells are never needed for anything including turkeys. The only place a 3.5" shell shines is in a goose blind with steel shot. All the crap in the magazines are pure bull when it comes to the 3.5" shell. When Mossberg first introduced the gun that would use this round, i was one of the first in line to order one and i can promise you that the only edge that load has is it's ability to give you brain damage! 3.5" buckshot loads will give you more than just a flinch unless your gun is heavy with a wide recoil pad.
