Its a can of worms to explain. Odds are,with technique,the dies you have will PROBABLY work.
But one of the advantages of handloading is tailoring ammo to fit your rifle. You have two rifles. One wears a 54 Long suit jacket,the other is a 38 regular.
You are the tailor.
I'll suggest you will make two different loads,one for each rifle.
I had two different 7mm Rem rifles. One a Husky 5000,a light,handy hunting rifle. The other a Win M-70 Classic Laredo. A heavier,26 in bbl ,longer range rifle.
They were chambered with different "headspace" tolerances.
When a gun is made, the chamber will have a feature that limits the depth the ammo will go into the chamber . Its the "stop".
It might be the rim,or the belt,or the case shoulder,or the case mouth.
The distance from the breech face to this "stop" feature is called "HEADSPACE"
That term gets misused a lot. Headspace is all in the gun's chamber.
We care how the ammo fits the gun's chamber. The space between the cartridge case head and the breech face of a round in the chamber is called "head clearance".
Obviously,we need some,to close the breech. With the exception of self-loaders,like a Garand, The Handloader often shoots for .002 in. The breech will close easily, but during firing,the brass will not be stretched excssively.
Study up in a loading manual about case stretch,case head seperations, the paper clip trick,etc.
Minimizing case stretch is a major factor in brass life.Its not unusual for 7mm Rem brass to have stretch rings after 4 loadings. With only one rifle.
7mm Rem and all belted magnums are designed to headspace on the belt.
The design was also toleranced so if you were in Africa facing dangerous game,it would not be finnicky. Some head clearance is intentional,and "number of handloads" was not a priority. About .005 in might be a typical factory head clearance.
One more factor you are dealing with. The belt is designed to be the controlling headspace feature. Competition from the case shoulder is not the plan. So the chamber will typically be cut deep enough to provide extra clearance at the shoulder.Again,production tolerances come into play.
The case shoulder will fire form to however your chamber was cut.
Advanced handloaders take advantage of the fireformed brass. They measure and adjust resizing to get that .002 head clearance from the shoulder for that particular rifle.
That does not work if you have two rifles with different chambers. I know that well.
I was shooting my Husky hunting rifle less than my M-70 Laredo. I saw a run of nickel plated brass came available. I ordered a few hundred for the Husky. I used plain WW for the M-70. I sized the brass to fit the rifle.
Reloading dies don't move the belt. They can resize the shoulder. You can obtain the means to take a comparative measurement from the case head to a diameter on the shoulder,and adjust to size back the desired amount.
Hornady makes a caliper attachment that will take that measurement.
I have not seen anything from him lately,but I will credit a Curmudgeon known as Mr Guffey with a technique.
If you need to size your brass a few thousandths shorter, you can do it in a measured fashion by slipping an automotive feeler gage between the shellholder and the case head. It will serve as a shim, and you may find what works.
Good luck!
One more thing. You can get interference on a length,or on a diameter. All that I wrote about was lengths. Some sharpie ink on the case will scrape off in the rifle if you have a diameter issue.
Use your calipers,too. For SOME rifles,particularly Remington semi-autos,small base dies can be an answer. But be careful. Small base dies are recommended for more often than they are the correct answer.
A die can be polished to have some bell mouth in mfgr. For that 1/4 in,the Lee die may have a bell mouth problem.
You can try another brand of die,or, I believe Lee might make a collet type die that might squeeze that last 1/4 in. I do not have such a thing,so I don't know for sure.
Also,make sure your press is not stretching or flexing under load. Ram up,under full resizing load, see if light can leak in to the space between the shellholder and the die.
