LR-308 (Anderson Arms) , getting ejected brass with a flat spot on the case neck. Not sure case will be reloadable. Not sure if it is happening ai the port or deflector. Any suggestions

If it's just a ding it will probably be fine when you resize it.

Should be fine when you resize it, just cosmetic.

Pictures of said ding?

The neck expander portion on the primer decapping pin of your resizing die will correct it. That's what they're for.

The downside is that if it happens a lot, your neck will work harden faster. If you are like most people and don't anneal your brass, this means it will be splitting it sooner than if it wasn't happening.

My suggestion would be an adjustable gas block to tune it so that the brass flies free.