The ass doesn't need to fit as it sticks out of the chamber in the RFB. Small base resizing isn't necessary.
You must resize the case body and bump the shoulder, though, if you neck-size only you will get a round stuck in the chamber at some point. Very, very stuck, don't ask me how I know...
My proven method is either to use a Lee full-length resizing die, or, for less run-out and less work-hardening of the neck, I use a Redding body-type die and then a Lee collet die.
Never had a feeding problem in the RFB and I mostly load to a longer 2.823" OAL, which is magazine length.
Sometimes loading issues are caused by the mags.
After dealing with tight spots and sharp corners on the mag itself, and you can push rounds smoothly out with your thumb, assemble the rifle without the top cover and without the bolt carrier and stick a loaded mag in. See how the rounds feed, with your thumb again. You can use then "finesse" tools such as a hammer, a 2x4 and a pair of pliers with electrical tape around the jaws to bend lips a little bit at a time, until they chamber easily.