A couple of things to try in resizing. Re-lube the tight cases and run them up into the sizing die and count to five, lower the press ram and count to five again, then raise the ram and count to five a second time. This usually knocks a couple more thousandths off a military case shoulder length.
If that doesn't do it, note that most shell holders have the case slot cut a little taller than it actually needs to be to slip a case in and out. If you have a stubbornly tight case, take the decapping pin out of the sizing die. Put the fat case in the shell holder and slip a 5 thousandths automotive feeler gage into the shell holder slot under the case head. That will get you that much additional shoulder setback, which should settle the problem. You'll then need to put the decapper back in and run the case through again without the feeler gage so the expander can adjust the case mouth ID. You can sometimes even fit a 0.010" gage in, but you really don't want to creat that much additional excess headspace, as it shortens case life. Just use the minimum needed to fire the cases once in your gun.
Once that's been done, the normal sizing die setup is likely to work just fine for you. The problem here is that the amount of shoulder setback being asked for is greater than would be the case if these cartridges had been fired in your chamber originally. All brass has some elasticity, so the longer it is when you run them into the sizer, the longer it tends to be coming out, up to a point. In sizing LC .30-06 fired by a large number of different Garands, I noticed about 0.005" variance in shoulder setback coming out of the sizing die the first time. That's when I figured out the run-back-in and rest it method. A lot of people also but a separate small base die, only to discover they only need it the first time they size once-fired brass, but that a regular sizing die works fine for the same brass thereafter.
One way around the extra work is to buy your once-fired brass from
Scharch Manufacturing (Top Brass brand). Their's is processed. That is, cleaned, sized, and the crimp removed. Others may offer that service, but I am only familiar with this outfit.