Ridges on case neck after sizing

[JohnKielly]

It happened to me with .308 FLS dies I'd used for some years & turned out to be crud building up on the neck/shoulder junction of the die when I had a close look. I polished it off with J & B on an oversize Parker Hale style jag turned with a cordless drill & that worked until I upgraded to bushing dies..

 

[KMart]

My fix was to run the cases through walnut media for 4-6 hours, expand the necks, then chamfer the outside of the case mouth. There is a small lip on the outside of the case mouth that must be soft and peels off in the die. You can feel the ridge with your finger nail

 

[ballison]

This subject has been talked about before with Lapua brass. It is the brass NOT your die, untill you size new Lapua brass, then you get the lines. Even if you polish your die and size some more new brass it will happen again.
You can either run your brass in your polisher for a while or wipe the necks with some sort of cleaner ( I have used alcohol or lacquer thinner ) then you won't get the lines. This drove me crazy for a while till I figured it out and I wasn't the only one.
Tarey
Just try it. ;D

Agree! I get it ONLY with virgin brass. It goes away after the first firing, so there it is nothing in the die or bushing. I also stopped sizing virgin brass and only run an expander mandrel through them to take out the kinks.

 

[fguffey]

I got the scratches and marks on my cases and they were not Lapua brass, so there goes the Lapua theory. :

The dies transition from the shoulder of the die to the neck is rough and scratching your case necks. Chuck the appropriate size shot gun cleaning mop in a drill and apply some J&B bore paste, Flitz polish, automotive rubbing compound etc. and polish the die, while moving the mop back and forth.

RCBS did a bad job polishing the new die 'BUT" this can happen with any manufacture, return it or polish it, its your call.

I had this happen with a new Forster die and polishing fixed the problem.

RCBS did a bad job on the transition? And then you flitzed it and fixed it.

And now I am to believe you when you discount another members effort.

F. Guffey

 

[butchlambert]

I've never had that problem, but I use carbide bushings.