light did you put that cartridge in the mag and chamber it that way or did youjust drop it in the rifle and run the bolt closed?
If you put it in the mag that could account for the two spots where it was rubbed off. Try seating a bullet like you would normally do.
Color the case up to the case mouth and color the bullet as well.
You could have a short throat and you could be jamming the bullet into the rifling. That unto itself is not a bad thing you just have to adjust your load accordingly.
If you have a tight neck and a short throat your going to find out with a bullet seated. That is what I am thinking.
You may need to invest in a neck turning tool. You can always call your smith (Who I am sure would want to help you find out what is going on) and ask him about your problem. Me may be able to say oh yeah I chamber to the SAMMI min specs so you may need to trim and turn the necks.
Hornady Manufacturing Company :: Reloading :: Metallic Reloading :: Tools & Gauges :: Case Care :: Neck Turning Tools
I would pick one up and just uniform the case necks and see what happens.