I thought about the 3.5 shells, but in order to build this as a mid level (recoil) one would most likly end up having to either put a lot of filler of some kind, or move up a bit in powder. I talked with my smith last night, and recommends going FFg and the 2.5 in shells and probably 700 grain bullet. All of this at this point is up for grabs as the gun has not been built. I does have the greener style cross bolt, and very heavy underlugs too. The other thing to think of is where to get the dies from for the 3.5 inch RMC cartridge....and they are more than 7 times the price per unit.