You are probably at this point starting to run the solid base of the case into the die as you try to push the neck down and back that last little amt.
The solid base of the cartridge case is just that and doesn't want to resize at all as easily as the upper portions.
It takes a very powerful press to push a case head into the die. Some cases are thicker than others farther up from the solid base as well so you start to run into resistance sooner.
Many single stage presses have simple leverage systems that work very well for most loading. But just don't have the power for case forming and swaging.
If you do get the case fully seated in that die, there's a good chance pulling it back out will rip the rim off the case and leave you with a rimless version of the case stuck inside the die.
The rim is not a very strong piece of metal to yank on to pull the case back out of the die considering all the force you are needing to get it in there.
Some 'make' the the smaller and simple leverage presses work by placing an extension handle (piece of pipe) for leverage over the press handle.
It may work, but the chances of springing the press are there or breaking linkage parts, ect.
Check the base dia of the brass you are reforming and make sure first that it's not oversize to begin with.
That would be making the press and die work extra hard in reforming that when all you really want to do is neck down the mouth and then push that new shoulder back.
