case separation

[dadswickedammo]

Had three cases separate thought it was from large dings in the cases from last firing you all have talked me out of that some pix were posted that were just like mine.
Now i have been told exes headspace i insure my cases are at or below max size.
Weak brass just went out and inspected about 200 cases no ring no wear i could feel with a paper clip.
all my loads are well below max 55gr fmjbt 23.5gr tac shot from a new saiga with a 21.5'' barrel.
What do you think.
THANX for all your input

[swerv512]

hard to tell without pics of the separated cases....
headspace involves two different measurements- one for your rifle's chamber and one for your loaded ammunition.

you should be using a precision micrometer to ensure that your handloaded rounds are matched to your rifle's chamber. just because your handloads are within saami headspace range doesnt mean your chamber is....

[Antihero47]

You need to have your rifles headspace checked. Either you or a gunsmith need to check it.

Its either your rifle, OR you are over resizing your brass and pushing the shoulder back too much. I recommend getting a case gauge with the calibers you are reloading and check your loaded ammo.

[dadswickedammo]

over resizing?

what do you mean by over resizing?

[sonnyt650]

I believe that typically full-length sizing dies will get you very close to minimum dimensions all around. Logic dictates that factory barrels have generously cut chambers meant to accept anything up to the maximum dimensions for the cartridge. For these chambers cases are expanded to maximum dimensions through firing, then pushed back down to minimum dimensions.

For firing from a single bolt-action you can push the shoulder back down so that it just fits in the chamber. To accomplish that you'd need some tools to determine how much you need to push the shoulder back, though this way the brass isn't worked as much every reload. For semi-autos I don't know how well such ammunition would feed, and I don't want to have to pull a hundred rounds if it doesn't.

[swerv512]

For semi-autos I don't know how well such ammunition would feed, and I don't want to have to pull a hundred rounds if it doesn't.

i usually bump 0.001 in my bolt actions and 0.004-0.006 in semi autos depending on the chamber. never had an issue.

[J-cat]

what do you mean by over resizing?

When you fire a factory bottlenecked round in a factory chamber, there is about .010" clearance all the way around- the case head, the shoulder, and the neck. The case expands to seal the chamber and then springs back about .001" so that you can extract it.

Now you have a case that is about .009" larger than it used to be and needs to be resized back to factory specs for reliable feeding. A typical sizer die, if adjusted to touch the shell holder, will resize the case back to factory specs or even more depending on QC. This means the shoulder of the fired case will be pushed back about .009" or more if you adjust your die that way (which BTW is how the die manufacturer wants you to do it).

The problem with pushing the shoulder back .009" each time is it causes the case walls to stretch during firing and thin in the case body which leads to separation. To prolong case life, we adjust the sizer die to not touch the shell holder so that the shoulder is pushed back just enough to chamber, usually .001" to .005". This minimizes case wall stretching and doubles or even triples case life.

[FLIGHT762]

Without having some kind of measuring gauge, you don't know how much your dies are bumping back the shoulder of your ammo. Here's a link to a short article with photos to help explain the proper resizing issue so you may understand better. This article uses the Hornady headspace gauges to measure.

http://www.inlandshooters.net/index.php?contentid=99

I had someone give me some fired and resized 300 Win. Mag. cases. When I measured them, I found the shoulders were set back .025" over what they should have been. That could cause the issue you are dealing with. I once used a .222 Remington die that bumped the shoulders way too far and got case head separations similar to your issue, except, my cases separated lower on the case.

I use the Hornady and Sinclair gauges. You can use the Wilson / Dillon style drop in gauges or the RCBS precision mic. I like the Hornady / Sinclair style because they will gauge nearly all bottle neck cases using their set. You just need the gauge set and a digital set of calipers.

[thomashoward]

Had three cases separate thought it was from large dings in the cases from last firing you all have talked me out of that some pix were posted that were just like mine.
Now i have been told exes headspace i insure my cases are at or below max size.
Weak brass just went out and inspected about 200 cases no ring no wear i could feel with a paper clip.
all my loads are well below max 55gr fmjbt 23.5gr tac shot from a new saiga with a 21.5'' barrel.
What do you think.
THANX for all your input

At or below max size??? Its the below max size that is getting you in trouble.You should see a hair of daylight between the shell holder (a blonde one) and the die. If the ram is smashed down to the ram popover it is setting your shoulder back so when the cartridge is fired it has extra distance to fill up the chamber thus stretching the case to break point. I do nothing but neck size and all is well for the last 30 years.