I had the same problem with my Redding 260 die and my RCBS 30-30 die. What I actually discovered to be the problem was the tumbling media I was using. I was using the treated Lyman media. I found out these types of media have like a jewelers rouge in them and it will leave a coating on the cases. If this gets built up in the sizing die it can be very abrasive and scratch your cases.
I switched to a plain corn cob media and have not had any more scratching. I cleaned up my sizing die with JB.
Al

Haha!

Yes, my necks were properly lubed with Redding Imperial lube. The brass isn't scratching the die, it came from the factory like that. Machining marks. They must have some new guys like you working there.

I don't have to repeatedly polish the die. It is a one time deal.

Drink one for me. Wish I could kick my feet up on your bench and share one with ya.

OK, I will give you that it was maybe a rookie doing the final lapping of the finished surfaces. This is a step done, I believe, with a formed soft mandrel and varying grades of abrasive compound by hand. Maybe it is done with NC machinery..who knows. It is how we micro polish irregular inside diameter surfaces in the shop. It is highly possible the tangent point of the neck-shoulder junction was rougher than final spec. You are forgiven, job well done.

Bob Mc Alice wrote: You are forgiven, job well done.

Ok, how do I make this my signature?

shakes wrote:Thats exactly what they look like; the before picture. Ive got a big tube of flitz at home and will try that. The die is brand new from redding so I was a little dissapointed that it would leave scratch marks like that. Thanks Trent

Shakes, one more thing you may want to do before reloading those 50 rounds that have scratched necks. Polish them before reloading them so as to stop the vicious circle of die scratching brass and brass scratching dies. If brass is not cleaned very well and lubricated with time they could scratch the sizing die which in turn will scratch other pieces of brass. It has happened to me.

McAlice is correct about lubing necks....and about lubing brass scratches come from the die...either the die itself or the sizing button. I use Wilson dies with a button because my chamber has a custom neck requiring case turning. You cannot polish out the scratches in the die or button without challenging concentricity and correct sizing diameter. If the interior of one's dies are that rough...get better dies or a new button. Polishing removes material and the "how much" is a mystery.

I have been reloading CF for many years and some of my dies are from the late 60s. I have never had the problem you are describing. But.......... I ain't seen it all and I guess I never will.