Here is what is happening, I am just starting reloading for my savage. My recipe varies so far in total length (TL) and Charge and it goes something like this.

Bullet: A-Max 168gr
Powder: IMR4064
Primer: Winchester WLR

168gr.
TL 2.75"
Charge: 10 count of 42, 42.5, 43, 43.5

168gr.
TL 2.8"
Charge: 10 count of 42, 42.5, 43, 43.5

168gr.
TL 2.85
Charge: 10 count of 42, 42.5, 43, 43.5

About a week after testing these loads I started cleaning the brass when I noticed this: https://7w3qfa.bay.livefilestore.com...738.JPG?psid=1
What is causing this?