Guess what caused this ?

[Dustbuster]

I know what did, just wanted to get some group input before posting the problem and solution. The pic will show a bulge at the shoulder of these cases. They were not fired but were pulled apart.
https://www.dropbox.com/s/3le2acmtvk61d8g/Photo%20Jun%2023%2C%209%2015%2008%20PM.jpg

[Guest 6.8 AR]

Improperly sized due to the die going too deep? I guess I should have said the seating die

not set right. I've made a mess of a couple of them like your pic.

Edited June 24, 2013 by 6.8 AR

[mikegideon]

Yep. Roll crimp on the seating die set way too low. I've made some of those myself :)

[Westwindmike]

Yep, over crimped.

[Dustbuster]

300 blackout,i was messing with a lee crimp die after using the built in oem taper crimp die and this is what i got. Doesn't take much to get that awesome shoulder but....a small bit of CCW adjustment did the trick to avoid damage.Have been using both a Hornady set and RCBS 300 AAC set. not sure which i like more or less,all fun to work with. On an addl note the rcbs dies have a tc on the side which indicates that die will produce a taper crim v roll crimp. ( and yes I did RTFM) lol Edited June 25, 2013 by Dustbuster