Cause for neck splitting?

[tstowater]

Several good comments on why the brass split. What I have been told/learned over time is that brass becomes brittle from overworking. This can be a product of times fired or resizing too much. .008 seems like a lot of expansion from a loaded case to a fired case. Annealing will help extend the case life, but may not be the complete solution.

I did a little calculating: assuming a bullet at .224 (using .2245) and a Lapua case neck thickness of .0135 (based on the new case I measured this morning) should give you a loaded case of .2245+.0135+.0135=.2515. This would be a whole lot less than the .008 that you are expanding. .004 is still plenty of expansion and you may want to go to a neck die to limit overworking the cases. I would suggest annealing periodically to extend brass life.

New R-P cases don't have the same case neck wall thickness (I checked several this morning they are closer to .011 to .0115). This will likely cause a larger expansion as the overall external case neck dimension of a loaded case will be smaller. Based on this, the R-P cases are going to have to worked more and likely be a cause of the split cases if you don't anneal.

[coyotespotter]

I have had older reloaded brass/bullets cold weld, these were sitting for about 10 years. Fired a couple and split the necks. Pulled the remaining and annealed the brass,reloaded to same specs. No more split necks. This was factory 17 rem brass.

[Bill K]

Granted brass can have the cases split, mostly in the neck area, but sometimes in the body, due to various reasons, but the two most common is caused by overworking and not annealing and too tight a neck when seating a bullet. Bill K

[mefizto]

Hi Bayou City Boy,

thank you for your explanation how the oils presumably do. The only issue I see is your assumption that Dean2, performed the same experiment as SAM and in longer time lapse from applying the oil.

Thus to clarify the issue for myself, I have pushed out ten of the primers for experiment and fired the remaining ones. I intend to repeat SAM's experiment with different delays between a pair of primers. I was thinking about a week between trying to fire each pair, which would give me five weeks from removing the primers form oil. Do you feel that this time is sufficient?

Hi tstowater,

My numbers agree with yours as far as Lapua is concerned, but as I noted the Remington cases had different outer diameter of the neck when loaded. As you may remember the difference between the round and the chamber was my hypotheses, but it seems that most commentators disagree.

In any event, I have disassembled the cases and now I am reading on annealing, to do it right. I also plan to measure the chamber.

Hi coyotespotter, Bill K,

very interesting comment about the case/bullet weld and too tight neck. Yesterday, when I was disassembling the rounds, I noticed that some of the bullets were really difficult to pull, others just needed minor force.

On an related issue, some of the Remington cases appear to be new, never loaded. I have not find any article claiming that brass embrittlement is caused by age; so do I need to anneal these?

Kindest regards,

M

[Bill K]

so do I need to anneal these?

Kindest regards,

M[/quote]


I will not hurt them and may just save you some case's. I would just go ahead and anneal them and start off on the right foot, so to speak. Bill K

[coyotespotter]

Much easier to pull cold weld ammo if you seat a couple thousandth deeper, right before pulling. Especially important with light bullets and hammer style inertia puller.

[mefizto]

Hi Bill K,

thank you, will do.

Hi coyotespotter,

ha, ha, should have known yesterday,

Kindest regards,

M

[TinMan]

Just an experience. I have four 22 Hornets, a No.3, a CZ 527, a Cooper M38 and a Kimber M82. I neck size only after fire forming, use all W-W brass, and segregate the brass to each rifle, and anneal that rifles brass when necks start to crack. Each rifle has a different size chamber, all factory chambers. From biggest/sloppiest chamber, the No.3 requires 3 reloads before annealing, the Cooper and CZ each require 6 or 7 reloads before annealing, and the Kimber can go for 15 or 16 reloads before annealing. It also depends on what dies you are using.

Ammonia also embrittles brass, as the links state, so don't use any polishes that contain ammonia compounds (like Brasso).

[mefizto]

Hi TinMen,

. . .and anneal that rifles brass when necks start to crack,

Is it not too late?

Kindest regards,

M

[TinMan]

It is rare for more than a couple pieces out of a box of 50 or 100 crack. You toss those that crack, and anneal the remaining pieces before reloading.