Buckled brass???

[renegadeg2]

I Need help or guidance.

I'm relatively new to reloading, but have successfully loaded 223, 3006, 9mm...

Reloading 300wm yesterday,
1f brass.
Ladder load.
Case full length resized, bumping shoulder by 2 thou or so.

Seating a light 150gr bullet (so ignore the cannelure on the pic). Bullet seated 20 thou off the lands.

I prepped my seater with a dummy round before starting my batch of ladder loads. It looked absolutely fine, with correct measurements all over. Seated with crimp, which felt fine at the edge of the neck...(sorry, I dont have that pic). Using hornady equipment.


When I started to seat and crimp the powder-charged rounds (which is only 80% capacity of case)... this is what started to happen:


What gives???

Mind you, it was 2am and I cant identify what went wrong. I followed the hornady instructions exactly.

Please advise me.