Case neck cracks

[Bluejay]

I was shooting my rifle yesterday to finally check it with the load I am going to use for this coming season (starting August 16 btw) and I had 3 cases (out of 12) with cracks in the neck.
According to the Lyman reloading manual, those should result from “case fatigue”.
I was quite surprised, mainly because this is the first time something like this has happened but also considering the following:

I am shooting .264” 120 grs. Nosler Ballistic tip in a 6,5x57R caliber - K95 Blaser single shot rifle – Norma 204 powder and Federal 210 standard primers and RWS cases.
No sign of high pressure at all from this load (which is 2 grains lower than my maximum I have tested)
All cases had the same background, coming from stock ammo’s plus two re-sizing (thus were on the third time shoot).
The load I am using has already been tested before without problems.
Bullet has a very “relaxing” free boring (approx. 3-4 mm. off the lands).
I have been using RWS cases up to five times with no crack problems.

The only guess I have is that (maybe) I have previously loaded these cases with a higher volume of powder, thus getting high pressure (even though got no signs of it) and stressing the cases.
Otherwise, I have no idea why I could get those cracks after just 3 shots.

I am shrinking your brains on this one.

Thanks for your help.

 

[rick smith]

Any idea how old the cases were when you got them? How much are they expanding upon firing vs. how much they are sized before loading? Its not just what is loaded. Rick.

 

[TCBrian]

I have had a few case mouths split in a 6.5x55 when using average loads with 120 BTs or 140ssts. It was after the cases were loaded about 5 times. I just use that as a sign to disgard the lot. The brass never showed any other pressure signs, but that was enough for me. If the necks are brittle, the web area could be getting thin or other problems could occur, better to start with some new brass. You probably just had fatigued brittle brass. Anealing the necks would probably get you another couple loads, but why bother, throw them away and keep track of the number of loadings next time to see how long it takes for them to get brittle, then stop one load before that, so it doesn't happen again. I think the throut in my barrel is quite large too, making the neck have to expand a lot, then sized back down. Eventually the necks will get brittle.

Good shooting,
Brian

 

[remingtonman_25_06]

WHen I was loading my 220 swift with winchester brass, I would get split necks on the 2nd firing or 3rd firing on some of the cases. Not to many, like 5 out of 100. The load was not excessively hot, I just think that winchester brass is not that great for 220 swifts pressure or something. They werent big ones either, just little tiny ones right in the neck area. They always said a 220 swift was hard on brass, but I didn't know they would be that hard on brass.

 

[clearwater]

I got a batch of new brass that showed split necks after the first firing, even with
light loads. Called the factory and they had me send them some. They sent me a
check to get new brass after seeing them and told me to throw away the rest, bad annealing at the factory.

On a rare size case like 6.5x57R I would likely anneal them and use them for practice loads if the factory wouldn't replace them.

 

[Bluejay]

I have had a few case mouths split in a 6.5x55 when using average loads with 120 BTs or 140ssts. It was after the cases were loaded about 5 times. I just use that as a sign to disgard the lot. The brass never showed any other pressure signs, but that was enough for me. If the necks are brittle, the web area could be getting thin or other problems could occur, better to start with some new brass. You probably just had fatigued brittle brass. Anealing the necks would probably get you another couple loads, but why bother, throw them away and keep track of the number of loadings next time to see how long it takes for them to get brittle, then stop one load before that, so it doesn't happen again. I think the throut in my barrel is quite large too, making the neck have to expand a lot, then sized back down. Eventually the necks will get brittle.

Actually, I do not think the throat in my barrel is large at all.
In fact, I can not push a bullet into a fired case without resizing.

Trowing away the cases is no big deal at all, but the thing that matters (since I am hunting) is that I will have no drop in accuracy or dangerous outcome for my rifle or myself.
Am I safe on this side?

Also, cases where fairly young and RWS are usually known to be good quality ones.
Last but not least, 6,5x57R caliber should not normally be a "high pressure" one and RWS must have good experience on it, since it is a very old one (coming from 8x57/7x57 Mauser).

I don't think is the case, but could it be some debris stuck into the throat?

Thanks for you attention.

 

[rick smith]

Please explain "I can not push a bullet into a fired case without resizing." If the neck is that tight, you could be building high pressure with a low pressure load. You would need to think about turning the necks.Rick.[/quote]

 

[Bluejay]

Please explain "I can not push a bullet into a fired case without resizing." If the neck is that tight, you could be building high pressure with a low pressure load. You would need to think about turning the necks.Rick.

[/quote]

Sorry Rick,
I have expressed myself in a wrong way (my english is slipping away... ).
What I meant was....I could put a new bullet into a fired case without resizing, since the neck results to be pretty much the same as a resized one and that shows (IMO) that the chamber tolerances are built quite well and there is NO excessive expansion of the necks, thus not being the cause of those cracks.

 

[rick smith]

You should be able to put a bullet into the case neck after the case has been fired without any sizing. But the amount of clearance is the issue.Rick.