FL Sizing, Necks getting grooved.

dgradinaru

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For the long time reloaders out there. Have a couple dies I've been using for 10+ years. Just recently I started to notice the necks of my cases getting grooved, scratched while sizing. Would this be an indication of needing to deep clean my dies and scrub them in solvent, or parts cleaner?

My proven loads that would average 3/4"-1" have opened up as well. So it seems it also effects my accuracy. Any help/ pointers will be appreciated.


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I had something similar, but from memory mine was worse. It was actually making the neck too small, and my neck tensions was too tight and I was crushing the shoulders. It was bad. I might still have a couple if I dig them out for pics.

Anyways, yes, just a quick clean and everything was good again.
 
20250813_174150.jpglooks like the scoring wasn't as bad as I remembered, and hard to get a picture of, so likely the same. You can see how much pressure was on the bullets too.

Edit to say I don't use the expander ball, and im not sure what was going on that my mandrel didn't open it up enough on the first pass? I do a giant batch, so maybe the time between mandrel and powder and seating was too much? I ended up running them through the mandrel again immediately before seating.
 
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View attachment 995088looks like the scoring wasn't as bad as I remembered, and hard to get a picture of, so likely the same. You can see how much pressure was on the bullets too.

Edit to say I don't use the expander ball, and im not sure what was going on that my mandrel didn't open it up enough on the first pass? I do a giant batch, so maybe the time between mandrel and powder and seating was too much? I ended up running them through the mandrel again immediately before seating.
incorrect set up
 
incorrect set up

Feel free to.. expand on that.

Yes, maybe tumbling and having shiny brass would have prevented it, but I've run thousands of rounds through that set up. Works just fine. But im always willing to learn a different way.

Anyway, to clean the die I just used the same stuff as cleaning my barrel. Its what I had on hand. Again, I don't run the expander ball so I had a clear shot right through the die, just patches and brush.
 
What does the neck look like after you clean it? Same marks?

OD of neck after firing?
OD of neck after sizing?
OD of neck with bullet seated?
 
Clean your dies!

You wouldn’t put dirty oil in your car why put dirty brass in your dies. A short tumble to clean em up and then run them through.

Not sure on what your reloading process is but this may be the case. I’ll clean my sizing dies after every reloading session. (100 - 300 cases)

Also, just clean the die with brakleen once it’s all pulled apart. Can’t see why you’d need steel wool.
 
View attachment 995088looks like the scoring wasn't as bad as I remembered, and hard to get a picture of, so likely the same. You can see how much pressure was on the bullets too.

Edit to say I don't use the expander ball, and im not sure what was going on that my mandrel didn't open it up enough on the first pass? I do a giant batch, so maybe the time between mandrel and powder an much better thand seating was too much? I ended up running them through the mandrel again immediately before seating.
Jeez, don't let the "gun writers see that or they will become examples of the latest greatest whiz bang super dooper cartridge that is sooo much better than anything else on the market. :p
 
The markings on the exterior and interior of the necks looks to me as being too symmetrical to be caused by dirty /rusted dies. Usually the drag marks from dirty dies will scratch the outside of the necks but not the interior.

What brand of brass are these?
 
RCBS brand. I had a spare set of new dies, sealed in the box that I opened last night, deburred, chamfered the brass sprayed it with lube and this is the way it came out. I've been reading up on this and a few from other forums have made mention that the die needs to be polished.

PNlorxq.jpg
 
If I am reading the OP's post properly these marks are being made using 2 different sets of dies.
Yes, two sets of RCBS dies. My first set never did this before, just started recently. I let it soak in solvent and lots of debris came out, finshed cleaning it with brake kleen and blew it off. Still does the same thing. I opened a new set, with new Norma brass, well lubricated and it came out with the marks as seen in the last picture with the barnes box.
 
I suspect the marks could a result of very slight irregularites in the brass thickness of the necks during their forming at the factory.

I would try a different brand of brass and see if the markings still appear.
 
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