I have heard of this happening with this caliber,..and last night saw it for myself. The load was 94gr of retumbo behind a 162gr a-max in a sendero SF. The same load printed ~.5moa last weekend with a temperatire difference of no more than 10 degrees. Lst night on a hunt,..a buddy fired one more and the case came out with 2 collapse marks just under the body/shoulder junction 180 degrees apart. The barrel was completely clean and dried,..the chamber was dried, and the bullets are at the lands. Anyone have any idea what causes this in this caliber?