Strange Axial Marks on Case Necks

[sacto929]

This evening I started sizing some 7.5x55 Swiss brass for my K31 and discovered the axial marks on the case necks as seen in the photos below. The grooves are not just in the lube, but actually have some texture to them in the brass. I have not seen this before and figured that I'd ask the community for any experience with this.







Particulars:
--Brass: Prvi, 3rd loading
--Lube: Castor oil
--Dies: Redding 80235 (for K31), taken apart and swabbed with IPA and Q-tip after first notice. Die is set according to Redding directions.

Any ideas?

Thanks!

[CSACANNONEER]

Got me but, I'm interested in finding out.

[Gowking]

Polish the neck portion of the die.

[LynnJr]

It looks like the expander is leaving those marks.
If you use steel bushings in a bushing type die instead of the coated bushings you get those marks as well.I realize your die doesn't use bushings just a heads up to those viewing this thread.

[sacto929]

i can try to polish the neck portion of the die and the expander. This is the sixth of seventh time I've loaded with these dies and the first time I've seen this faceting around the neck.

[Discogodfather]

On the gun side, anything showing inside the chamber? How is the lead?

[Spyder]

Every .308 piece of brass I've ever resized in my die is like that.

Irritating, and I keep forgetting to ask what causes it.

So, tagged for an answer.

[sacto929]

On the gun side, anything showing inside the chamber? How is the lead?

I haven't looked at the chamber itself, but the post-fired, pre-sizing brass should be the negative. It is perfectly smooth and seemingly uniform, so I don't think that's the source.

[ckcadavona]

My brass gets like that when I don't clean my dies. Seems like the residue builds up and forms vertical lines as the brass is pressed in and out.

['ol shooter]

I bought a large amount of used 30-30 brass a while back, and some of them sized like that. I figured it may be that they were shot in a firearm with a loose chamber. They did not look as bad as yours though. The ones that did it also needed their shoulders bumped, and had to be trimmed.

[Flyin Brian]

It looks like the expander is leaving those marks.
If you use steel bushings in a bushing type die instead of the coated bushings you get those marks as well.I realize your die doesn't use bushings just a heads up to those viewing this thread.

My bushing dies must be broken because I am using steel bushings and don't get marks like that

[Guisan]

What do the cases look like when you fire GP11 ?

[0321jarhead]

This evening I started sizing some 7.5x55 Swiss brass for my K31 and discovered the axial marks on the case necks as seen in the photos below. The grooves are not just in the lube, but actually have some texture to them in the brass. I have not seen this before and figured that I'd ask the community for any experience with this.


Particulars:
--Brass: Prvi, 3rd loading
--Lube: Castor oil
--Dies: Redding 80325 (for K31), taken apart and swabbed with IPA and Q-tip after first notice. Die is set according to Redding directions.

Any ideas?

Thanks!

I believe you got the Redding Stock number a bit twisted. How about 80235?
Just recently bought the same FL die and resized the 2nd time with the PRVI with no issues at all.
Have you noticed how the necks look after they were fired? Maybe its the castor oil. FWIW, I use Imperial. Have you tried other lubes? When was the last time you cleaned your die?

[LynnJr]

My bushing dies must be broken because I am using steel bushings and don't get marks like that

Your most likely lubricating your brass on the necks before sizing.With the coated dies you don't have to lube your brass's necks.

[sacto929]

What do the cases look like when you fire GP11 ?

I have not fired any GP11 through this rifle, so I'm not sure. The cleaned, unsized brass (PRVI) is smooth on the necks.

I believe you got the Redding Stock number a bit twisted. How about 80235?
Just recently bought the same FL die and resized the 2nd time with the PRVI with no issues at all.
Have you noticed how the necks look after they were fired? Maybe its the castor oil. FWIW, I use Imperial. Have you tried other lubes? When was the last time you cleaned your die?

You're definitely correct on the die number, I got the 2 and 3 mixed up. Thanks for the correction.

I started using the castor oil based upon Latigo's recommendation and it's been working very well. I have used it in these dies for six previous loading runs through these dies without issue. Prior to the castor oil I used the RCBS lube, but it was a pain. I also tried the Hornady One Shot spray until I stuck a .30-06 case in the die. Castor oil has been good since then....

I broke the die down and gave it a thorough cleaning with a rag and isopropyl alcohol (IPA). The expander "ball" had some build up that took quite a bit of rubbing/twisting to get off. The residue would scrape off with my finger nail. It looked similar to compressed solids from molybdenum disulfide grease that I've seen deposited under heavy loads. Since there aren't any solids in castor oil, the mystery deepens....

I soaked the same rag in IPA and twisted it through the die body several times. I did this until the body was visibly clean with a light from both directions. The body at the neck area was smooth with only circumferential scratch/polish marks--nothing axial.

I reset the die and ran another case. The same axial marks/faceting was present. When I looked at the expander, I could see very light axial marks on it. I saw similar very light marks on the neck area of the body when the light was at the right angle.

I'm going to have to try to find a longer rod for my Dremel polishing tip, as the one I've got doesn't reach to the neck area. If anyone has any other ideas, I'm all ears.