I had a member over on EAA Firearms FB page that contacted me with the following:
Howdy. I have a 10mm question after my range trip today. What's the best way to send you a picture? I was terminal testing Prograde 140 TAC-XP and had two of three brass split. It was my first outing with the G29 gen 4 so I'm not sure if it was the pistol or the ammo. 125 grain TAC-XP brass didn't split.
I'm just waiting on the pictures to see if the 10mm crowd here can help us figure it out.
If he can send the split brass and maybe a loaded round of each bullet for pull down, we all can learn a little more.
When we did the pull-down on the ones you tested, testing showed;
Prograde 125gr TAC-XP
EAA Limited Pro 4.75" 1679, 1723, 1703. Average = 1701.66 FPS/ 804 LBS
Prograde 140gr TAC-XP
EAA Limited Pro 4.75" 1428, 1453. Average = 1440.5 FPS/ 645 LBS
Pull-Down info here;http://10mm-firearms.com/factory-10mm-ammo-pull-downs/prograde-125gr-and-140gr-barnes-schp-pull-downs/ (http://10mm-firearms.com/factory-10mm-ammo-pull-downs/prograde-125gr-and-140gr-barnes-schp-pull-downs/)
It would be nice to see the primers as they sit in the cases...
(https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xfp1/t1.0-9/10380309_712848508753184_8110955522053594659_n.jpg)
I have had that happen with Re-Use of Hornady Brass, usually that indicates that the brass is too stiff to expand without, thus cracks like shown. Could be over worked alloy and/or improper annealing to make the brass soft and malleable...
If I had to guess this is Armscor brass with Prograde headstamp. They are all under one umbrella now and a long while back, I had an Armscor brass split.