Problem with brass

[Troll_Toes]

I was resizing some brass and I noticed a ridge all the way around the case about  .1" up from the extractor groove. I stopped and measured some cases before I resized them at the same place where ridge was and they measure .432. The cases looked normal till I sized them then it showed up. I'm not  sure what is causing this to happen. 

The load was 7.7grs of True Blue 300CCi primer Starline brass and 200gr coated hardcast bullet from Missouri Bullet Comapny.

They were fired from a Glock 40 with a KKM barrel the rest of the gun is stock.  I cleaned the barrel and noticed there was leading in about the last two inches of the barrel. I measured the chamber with a Starrett hole mic and it measure just over .432.
I have two other KKM barrels for a G29 and G20  I measured those barrels they are .430 and .429 respectfully. 

Any thoughts on cause of the problem would be of great help.
Here is a pic of one of the cases.


[attachment deleted by admin]

[The_Shadow]

Are you using Hornady dies?  Are they a Small base die?  The sizer may be sharper than some others that have a radiused sizer ring.
If you use a pass through sizer prior to the regular sizing that may eliminate that issue!

[Troll_Toes]

I used RCBS carbide dies. I've been using those dies or about 8 years. I use the RCBS dies to resize and remove the spent primer then I use a Lee pass through set up

[The_Shadow]

I too use the RCBS dies mine are from 1990 vintage.  I have never experienced anything like you are showing in the picture.  The lines were not there prior to you sizing the brass?
If they were that would be a smiled case, however it does look like what I have seen some have gotten from their Hornady die sets.
Have you used any lube to see if it helps?

[Troll_Toes]

The lines are not there before resizing. I'll take the die apart and clean it and see if I can find anything.

[marlin39a]

Check the carbide ring in your sizer.  It possibly broke.

[Pctechdude]

I've seen this if the brass is ballooned out so far it will shave the brass as you're resizing. I bet if you check your die or your shell plate you'll find brass shavings. I would invest in a pass through die or a bulge buster die.

Sent from my Moto Z (2) using Tapatalk

[Taterhead]

Do you wet clean, by chance? With super clean brass it has a tendency to stick rather than slip under the sizing ring. It can gall ahead of the carbide ring. I like a little Hornady One Shot to let the brass slip inside the sizer easier. Makes the whole process more civilized.

[Troll_Toes]

I took the die a part and cleaned it. I could not find anything wrong. I did not find any shavings either. 

[my_old_glock]

I have seen it on some of my brass. The (Hornady) resizing die does it. I think it is from over pressure.



.