Working on reloading brass for the first time. This is once fired federal brass from factory ammo - all fired out of my rifle. I notice near the case head it’s a different color for the bottom 1/4” of the case. Is this the dreaded ring, or is this just the way it looks? I find it hard to believe that factory ammo is loaded so hot that it presents itself after 1 firing. This brass was cleaned by hand (tumbler is being shipped) and neck sized only. Thanks.