Thread: Ring/groove at base of case shoulder

Noticed in my 308 cases. Had a few reloads from them and sized once but getting a bit long now and was going to trim back.

Will have to bin them as looks like it will separate? First time I've had this in brass.



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Greetings @Tikka7mm08,
That looks wierd. Some more info would help like:
How are you sizing the cases?
How long are tey before trimming?
How long has the ring been there?
Do the cases chamber easily?
I have some ideas but it would be nice to narrow them down,
Regards Grandpamac.

Originally Posted by Tikka7mm08

Noticed in my 308 cases. Had a few reloads from them and sized once ...

This bit has me wondering...


It looks like a groove on the outside, is there a corresponding bulge on the inside?

Greetings again,
The case looks as though it has been neck sized. If this is so then the neck sizer needs to be cleaned and polished as it is scraping brass from the outside of the case. It may need to be replaced. It also looks as though the case is being sized to the base of the neck. It is better to just size around 80% of the neck. This together with I presume full length sizing can create problems such as a partially collapsed shoulder but we need more info to pin down just what is going on.
Regards Grandpamac.

Sorry. Sized I meant trimmed. FL sizing. Norma brass. Perhaps reloaded 6-7 times. Cases chamber ok. Group I shot this morning in 308 thread had them as does brass ready to shoot. It is quite a cut groove. I will check again but definitely will end up with case separation. I will try new brass and see what happens - bit baffled by this. I thought my outside deburrer might have done it but comes nowhere near it.

tis a new one on me.....

The op mentioned this occurred only after he first neck sized, after several firings and roads. Maybe clean the die insides with 0000 steel wool on an unmarked case and see if it still appears.

Only ever FL size...but is either die or chamber...easy to find out later this week.

Greetings again,
I think it is a fold rather than a cut. I also wonder if the badly scraped neck is somehow related. The neck just should not look like that after sizing. Are you using a good quality sizing lubricant and making sure that you lubricate the necks and not the shoulder. I have gone with a sizing wax applied with my fingers. Too much lube can result in shoulder and upper body dents. Using anything other than case lube is asking for trouble. My money is stlii on a slightly collapsed shoulder which may have problems sizing down. This could result in a fold just behind the point of the shoulder. A possible cause is a long case or more likely the rough neck on the sizing die plus a lack of lube on the neck. If you can't get the neck smooth you will have to replace the die.
Regards Grandpamac.

@Tikka7mm08 Do you anneal at all? Can you run something down the inside of the brass case and feel the same ( bump / hollow ) on the inside? If so, that could be indicative of brass flow... and thats more that one case??

Yes I anneal. Going to fire a factory case...check then vivid neck/shoulder and FL size to see what the die is doing. Will run die in sonic cleaner and give good clean. Will try later in the week and report back.

Can also get a headspace check.

sacrifice that case,run the hacksaw right down through it so we/you can see the area around the shoulder in discussion...PLEASE.

I will get dremel out later this week. There are a bunch like this that will all be going to the bin.

Bit of a mystery. So you're certain this wasn't there from the first fired cases?