deadduck357
Custom
The steel parts such as your selector, bolt catch, castle nut and end plate are Phosphate coated then an oil is applied. The oil penetrates/absorbes into the phosphate. During storage of the parts the applied oil can congeal and depending on the oil appear brown/orange. This is normal and nothing to be concerned about. Now some of your parts appear to have a brass color and I'm assuming this is due to you taking that brass brush that you mentioned to them.
As for the finish wear in the magwell, that is anodized and finish wear is accelerated with the use of STANAG mags. Yours looks like there was a mag or a lower receiver block inserted with a hard edge or burr. The receiver is made out of aluminum and won't rust so no worries. Aluminum can corrode through oxidation but you will be long dead before that would become any concern.
As for the finish wear in the magwell, that is anodized and finish wear is accelerated with the use of STANAG mags. Yours looks like there was a mag or a lower receiver block inserted with a hard edge or burr. The receiver is made out of aluminum and won't rust so no worries. Aluminum can corrode through oxidation but you will be long dead before that would become any concern.
