I had a Lyman full length sizing die that was leaving a thin but defined ring around the top (larger diameter) of the case shoulder. I took it to the gun shop and the guy there said I am adjusting my die too far down and it is damaging the shoulder. He said I should turn the die back out rather than screwing it down to preload on the ram.

I did it his way and had a suspicion that the die wasn�t coming into contact with the shoulder. Removing the pin from my 700�s bolt and chambering a sized case confirmed this. I couldn�t close the bolt if I tried with a hammer. This also suggests the shoulder to base length was actually longer. The RCBS precision mic headspace gauge established that to be true. Fired unsized cases have a slight spongy feel while sized cases done my way close with only the pressure of the ejector spring.

I just wasn�t comfortable with the die so I bought a new set of hornady dies. To set the sizing die I did as I always do for new dies/rifles. I measured a fired case in the precision mic, then adjusted the die down until the sized case was 001 to 0015 shorter. Giving me 1-1.5 thou headspace. Right? Have I done the right thing?

I read in most reloading manuals that the correct way of setting up a FL sizer die is to screw it down until it touches the shell holder then screw it down another 1/8 to � of a turn. However talking personally to people most say to take it back up 1/8 or more of a turn. I believe that every rifle, cartridge, case, die, press, shell holder, operator and more, will have a different effect on how it all needs to be setup. How can someone recommend a generic setting for everything and everyone? What do you think?

just out of curiosity,how far is the decapping pin protruding from the bottom of the die?

About 5mm. Why?

This is a tough one! If the problem is the decapping stem-expander ball assembly, try sizing a case with it removed. If it still doesn't chamber, adjust the die so that it just touches the shell holder and then with other cases, with it 1/4 turn more and then 1/2 turn less. You wouldn't think so, but different reloading manuals and die manufacturers make decidedly different statements about this. Lastly, it is possible that your Lyman FL die is defective. If so, you may want to speak to and/or return it to them. ...Maven

on my set of harnady dies,sometimes the sizer/decapper get loose protrude too far.When this occurs,i get the same ring you describe.