SmallCaliberCentral

I just purchased a RCBS competition Seating die for my 204 Ruger (Part number 39438). After getting the die adjusted and examining some bullets, I noticed very small rings on the upper part of the bullet. I am assuming that is where the bullet meets the part of the die that holds the top of the bullet while the cartridge move up over the bullet. This is a full ring on some bullets and on others it is only in some places (High Spots?) around the bullet. I first noticed them when I ran my fingernail over that area of the bullet. The bullet I am using right Sierra 39 gr. BK. I have not tried any other brands or sizes yet.

I am not sure if the problem is with soft copper in the Sierra bullet or too sharp of an edge on the die part that hold the bullet. I never noticed this problem when I was using the standard RCBS die that came with the F.L. Die set (Part Number 10301

Has anyone else had a similar problem?

I have heard that some people use Flitz polish (or similar) to polish out that portion of the die to eliminate that ring mark. Use a pad on a drill to lightly polish that edge that leaves the mark. My Redding Comp Seating die leaves light marks on my 39 SBKs, but they are equal ring marks around the bullet and they are light, so I haven't worried about it.

This actually occurs with all of the seating stems. Also has to do with how thick the bullet jacket is as well.

I drill seating stem out a couple drill sizes larger, allowing the seating stem to contact further down the bullet.

You can also apply some lapping compound to your bullet, cordless drill, and lap away.

One other problem that you have not discovered yet, almost all seating stems will contact the plastic tip of the bullets prior to contacting the bullet. The other reason I drill the hollow of the seating stem a couple thousands larger in diameter and deeper too.

I have been using that same die for my bullet seating since I got my 204, and I am using the competition seating die for my 223 reloads. I have seated thousands of bullets using these dies. I have not noticed the ring your are getting, so I just examined a few of my recent loads under my lighted magnifying glass. Under magnification I do see a ring on only some of the 39gr SBK's. I also examined some of the 32gr V-Max's that I have on hand. No ring on the copper part of the bullet, but I do see a mark on the polymer tip of the V-Max. I cannot feel either of them with my fingernail.
I believe acloco is right on, with his explanation of this.

on 39 b kings i get a ring around the bullet to, redding comp die

Thanks guys:

I got a reply from RCBS that they will be sending me a new replacement plug for this Comp. bullet seater die.
I also like the idea of relieving the area where the bullet tip might come in contact with the plug.

I will let you know how it works once I get the replacement plug installed.

I get the ring too but have eliminated most of it by polishing with a bullet point felt bob and compound in a Dremel. Light rings disappear with polishing, after the bullet is seated, using a few turns of 4/0 steel wool.

I have not received the replacement plug for my Competition bullet seater die yet.

In the meantime, I took the die apart and check the plug to see if I could see any burrs. It looked OK to the naked eye. So, I follow some of your ideas and used a 1/4" drill motor to chuck up a bullet. Then I added some BRASS polish with a Q-tip to the area that would contact the plug. I ran the drill at a very slow speed and rotated and rocked the plug against the rotating bullet. I did this with both a Horandy and Sierra bullet as they have different ogive (shaped tips). Once I was done, I used some steel wool to make sure there was nothing that would come into contact on the flat surface around the hole in the plug.

I also check to see if the hole in the plug was deep enough to clear the plastic tip of the bullet. It had more than enough room for both the Hornady or Sierra bullets.

After reassembling the die and trying it one some load.......No more marks. I think I'm GOOD TO GO!

Thanks guys for your ideas.