I just bought a set of Redding FL dies for a .223 Remington. Not bushing dies, but standard dies.
Cleaned the dies and sized a couple of cases to check function and concentricity. Useing my Sinclair concentricity gauge I found that concentricity was pretty good, less than 2 thousandanths runout on full lengthed cases.
BTW, cases are new unfired Winchester.
BUT, I noticed that the cases have an area about halfway down on the case where the die is making contact and appears that this is the only area of contact other than the neck. So halfway down the case it has a ring all the way around it that is about a 1/4 inch wide. This ring is not like the brass is being crushed or anything, just that it is contacting there and no where else other than the neck.
Looking inside the die it does appear that there is a dark ring or at least a different color or texture to the die interior that would correspond to the same area on the case. Is this is normal or do these dies need polishing and if so what is best way to polish the dies interior?
I do not like to oversize cases, so is it possible I just need to adjust this die up or down a bit?
I have reloaded for years, and tend to be a bit anal or perfectionistic about it, but this is something I have not run into before and want to know if it something I need to do something about or not.
Looking for any input and advice you might have to offer.

Thanks.

the die should be the same all the way. is it a rough spot? clean the die
use a tooth pic and detrmine if its rough.
I would not polish the die.
call redding and they may send you a replcement

Have you tried sizing a case on another die, or have you tried sizing a once fired case with this Redding die?

That will help determine whether the problem is with the die or the unfired cases.

Also, it never hurts to polish the inside of new dies with a dowel and cotton and a polish like Flitz (I have Simichrome which I think is pretty much the same stuff)if you haven't done so already.

I'll give those suggestions a try to see if it is the brass or not. I am at work at the moment, so will try this tinight.
Thanks for the input.

I don't care who manufactured the die, the entire inside of the die should be a flawless smooth finsih. If your die has a band that the finish is rougher at all, send that die back!
It is interesting it is just hitting on place on the case, but that probably has more to do with the cases not being fire formed, and this is the place where that die is contacting the case.....It isn't proper for a die to leave a 'ring' on your case when sizing it for usre though---I'd be returning it quick!

There's a good chance that whatever problem this die has, it may not be finish related. Redding will want it back so they can determine the source of its problem. Don't do anything to it. Swap it out with Redding so they can implement any needed corrections.

I can see the possibility that the base metal is inconsistent, resulting in uneven machining.

It could be the new brass was made with a bulge
that the die burnished. That would leave a ring
on the case and a ,ark in the die.
try a fired case with Imperial Die Wax and
see if the ring is still there.
Good luck!