Why am I splitting necks?

[Creedmoor shooter]

So I'm having issues splitting necks after 3-4 firings. I had this happen with norma brass after 3 firings and now with ADG after 4 firings annealing every reload. There must be an issue somewhere with it happening with 2 brands of brass. Loads are not hot. Outside diameter of the neck on the fired rounds is .395. This is a 6.5 creedmoor built on a savage action with a criterion barrel. I've read it could be a dirty die, which is possible as I haven't cleaned it in a long time

 

[wboregon]

What's the OD of the neck of a sized case, maybe you are over working the brass? Is there A LOT of resistance while seating?

Also could be excessive clearance in the neck, but since the brass comes out @ .295 (i'm guessing that's what you meant) then it would be surprising to see it shrink more than .001-.002 after firing

 

[243winxb]

395

Chambers are .297" +002"

Use a bushing die so the neck brass is not over worked.

 

[Creedmoor shooter]

Sorry I meant .295(fat fingers) lol. They dont go in the die mean but they can come back out pretty stiff

 

[bigedp51]

Chambers and dies can vary in size, what is the diameter of the resized neck before expanding and what is it after expanding. Look at table #2 at the link below at the amounts the neck is worked.

It could also be your annealing method is not making the brass softer.

That being said I have 30-30 cases over 25 years old that I lost count of how many times they were fired and I'm just starting to get split necks. And the cases were never annealed and I attribute this to a chamber and die closely matched in size.

Are Your Sizing Dies Overworking Your Rifle Brass?
http://www.massreloading.com/dies_overworking_brass.html

 

[tim_w]

Do you have pic you can load of the neck splits so we can see orientation and location. Such as are they splitting longitudinally starting at case mouth or possibly more laterally near the neck shoulder junction area. Also maybe a pic of one thats fired but unsized, then one sized, and finally one loaded. Focus on the neck area.


I would measure the size of a fired case neck OD (as its easier) and then one after the neck is sized. Figure the neck is expanding another thou more than fired measurement. How much the neck brass is moving gives an idea how much work hardening is going on. Also where and the type of splitting can offer some insight.

I agree with the statement about possibly impropper annealing is a likely cause. As unless the fire and sized are huge differences proper annealing should allow the necks to last longer. I have some cases fired thru even ARs that go 10+

 

[Creedmoor shooter]

I'll have to check later to see if I still have any of the ones that split. It's a vertical split that starts at the neck/shoulder junction usually going halfway up the neck.

 

[DUSTY NOGGIN]

I'll have to check later to see if I still have any of the ones that split. It's a vertical split that starts at the neck/shoulder junction usually going halfway up the neck.

IMO the die neck size is your culprit ( with use of that specific thicker necked brass ) , i believe it is sizing too small and your expander is having to open it back up , smearing the inner brass of the case , and starting that smearing action right at your junction

measure your expander button , check difference with bullet 264

measure brass neck after sized with expander removed


you might be able to neck turn your brass down to your existing die neck measurements , or get a type of bushing die to accommodate the other brass you may load for down the road ( brass neck wall thickness )

 

[Creedmoor shooter]

My dies are just standard hornady dies. I'd like to get a bushing die soon though so I dont have to deal with this. I turn my necks, but only enough to uniform the outside. I'll get some measurements for you guys later on this evening when I'm out of work. I'll measure a a fired case, loaded round, a sized case with the expander ball removed, and a sized case with the expander ball. Thanks for the help fellas, greatly appreciated. I'm sick of spending money on brass then having to toss it out after a couple firings. One thing I have noticed is hornady brass doesn't split. Those are fine. I'm assuming since I have hornady dies that's probably why.

 

[DUSTY NOGGIN]

My dies are just standard hornady dies. I'd like to get a bushing die soon though so I dont have to deal with this. I turn my necks, but only enough to uniform the outside. I'll get some measurements for you guys later on this evening when I'm out of work. I'll measure a a fired case, loaded round, a sized case with the expander ball removed, and a sized case with the expander ball. Thanks for the help fellas, greatly appreciated. I'm sick of spending money on brass then having to toss it out after a couple firings. One thing I have noticed is hornady brass doesn't split. Those are fine. I'm assuming since I have hornady dies that's probably why.

measure both brands brass same way and compare .

 

[Creedmoor shooter]

measure both brands brass same way and compare .

Good idea, will do tonight.

 

[Canhunter35]

Were these brass used with your reloaded 26 load firing those 140s near 3k?

 

[Creedmoor shooter]

Were these brass used with your reloaded 26 load firing those 140s near 3k?

No sir. The only load I ran in this brass was 41 grains of rl-17 at 2828 fps. The other stuff was hornady brass that lasted 8 firings before I got some case head separation.

 

[Canhunter35]

No sir. The only load I ran in this brass was 41 grains of rl-17 at 2828 fps. The other stuff was hornady brass that lasted 8 firings before I got some case head separation.

Since the hornady brass is lasting and the other isn't, the guys are probably right about the neck thickness