Split case on once fired ni plated brass

[BillC]

Yesterday I loaded 10mm for the first time. I used some once fired by me Hornady nickle brass, I believe I got from their critical defense load a couple years ago. I resized the brass and inspected did not see disformation, I used 9.6 g of blue dot, cci #300 , and a 180g XTP COL 1.260, after shooting 5 and recovering the brass I noticed one of the cases was vertically cracked and had black burn around crack. The primers were not flattened and the cases were not bulged. I've been reloading a couple years now but only reload once in awhile. So my question is, what is the most likely cause of this crack? These rounds were chronographed at average 1150, I used Lonewolf 6" bbl, reloaded with Lee 4 die set and measured each powder weight on my beam scale. Kind of creepy finding that case like that. Only happened with one piece of brass. could this just be a bad piece of brass or am I screwing up? I reloaded according to Hornady manual with the exception of the primer I used Cci and book used WLP

[oldman10mm]

No,you're not screwing up. Nickel plated brass,both handgun & rifle and from various manufacturers, has a long history of splitting. Don't know the reason why it does. Reload the ones that are OK and eventually they'll all be relegated to the 'to be recycled' brass pile. Not nickel plated brass splits too.

[tommac919]

I believe the nickel plated make the case more brittle and less 'workable'... maybe can't stretch as much

My common load is 10.4 of blue dot with a 180g head and RARELY have seen any splitting on the  brass I use. Don't think/remember seeing it yet on Starline brass which has gone at least 5x reloaded at this level.( but will prob happen sooner or later )

Only have seen it on some brass from certain companies now and then ( I save the off brands for when I can't recovered the brass )

[The_Shadow]

Hornady's brass is stiffer less malleable to start with, plus they are using faster burning powders in their factory loadings.
This adds up to an instant snap upon ignition than fatigues the casing itself especially in looser chambers.  Also the newer nickel plating process being used isn't like the older process and it too is stiffening the brass case.

Taking that into account you are resizing the casing, this work hardens it a little more and then you stretch it back with case neck expansion.  The case splits longwise in most instances.

I have had Hornady, Federal split as shot from factory loads due alloy properties and the use of uber fast powders.
Nothing to worry about other than the loss of a piece of brass...StarLine is a softer brass and is made with the reloader in mind.

[sstewart]

My nickel plated starling doesn't split more than the brass starline.

I use it to distinguish mine from my friends. (not a perfect system, but it works for us) He has some nickel and I have some brass. He keeps the brass and I keep the nickel.

[BillC]

Thanks guys, I thought I goofed up in the process. I'm going to load some more this week.