300RUM case failures

[jordanka16]

Since I'm using the rifle as spec and not a stated norm as I'm only loading for this rifle, I think its just working the brass harder to get to spec. From what has been said, casting the chamber would quantitatively be the spec, and again, for this rifle.

Well the idea for casting the chamber is to get an idea of how much the brass is being worked from loaded, to fired, to resized, to back to loaded. If the amount is excessive that could be what is causing case failure so soon.

 

[DizzyJ]

Using a comparator, Measure a fired case against a re-sized one.

 

[P7M13]

Had a shoulder split yesterday. Third firing, not yet annealed. The carbon track was the giveaway, though I scratched off much of it with my nail.
I usually just bump these, but this one got a full sizing last time because I moved my sizer die to a different press.
If I were to miss it on inspection, next firing it'd probably look like yours.
These were custom Hornady brass at $2 apiece. Grrrrr.

 

[Certaindeaf]

Try the 300VODKA, it's a lot better because if you put it up to your ear and listen closely you can hear when it's going to crack.

 

[P7M13]

Try the 300VODKA, it's a lot better because if you put it up to your ear and listen closely you can hear when it's going to crack.

Glad you still have your hearing. I guess you can also hear from the muzzle blast where the round will hit. Low and left....

 

[moose]

Had a shoulder split yesterday. Third firing, not yet annealed. The carbon track was the giveaway, though I scratched off much of it with my nail.
I usually just bump these, but this one got a full sizing last time because I moved my sizer die to a different press.
If I were to miss it on inspection, next firing it'd probably look like yours.
These were custom Hornady brass at $2 apiece. Grrrrr.

View attachment 439398

I am curious if there is internal erosion at the neck radius; there are a lot of hot angry molecules trying to make that corner.

Do you make your own brass? You mention custom, is it small batch from Hornady? You should try a neck resize just to see if the neck completely cracks.