I started talking with a fellow about buying his used RSM. After looking at the pictures of the gun everything looks perfect except for the it looks like the blueing on part of the gun is turn more "blueish".

Do any of ya'll know what causes this or what can be done about it? I'd really like to buy the gun if this can be solved (or maybe it isn't really a big deal). What do ya'll think? I've seen this on other guns, but have never really considered buying one like this.