I commissioned a set of custom loading dies for my 500 Jeffery. I wanted, or thought I wanted, an inline bullet seater. The guy that made the die set made the neck a little over sized in the sizer die. When the brass is full length sized and bullets seated, the bullets have minimal neck tension and bullets will spin in the case. I am using Horneber brass. I bought a set of RCBS loading dies and when used, the neck tension is correct. Bullets will not spin in the neck. I sent the dies back to the maker and he says he no longer does this work due to health concerns. He sent the whole kit and kaboodle back to me. Says someone else might be able to fix the sizer die. Any Ideas as to whom might be able to fix this mess??? I guess I can use the inline seater with the RCBS set and have a seater and a crimper. What do you do with the blankety blank full length sizer die???

if it can't be hardened and "pickup" a thou or to, or CPQ (i think thats the finish) and get a thou or 2, then your only choice will be to have it bored and an insert made, like the redding dies.

its a shame the maker didn't fix them or at least offer to do something for you.

ch4d will make you a sizer

I do have a RCBS set. I was looking to salvage this set as I think it was made to the specifications of my chamber. Whom would you suggest I have look at the die and see if it can be fixed? I just might have to scrap that sizer die and use the RCBS set. I did spend a lot of money on that in line seater. Almost $600.00. Call me a fool!

Maybe I'm not understanding you correctly, but usually neck tension is a function of the diameter of the expander in the sizer die, not the seater die. I have had a couple of die sets that had this same issue and polishing a couple of thou off of the expander did the trick.
I have to admit I'm not familiar with an "inline seater".
You might contact RCBS and ask them if they could look at it for you.