Open carry with a 1911A1? I like a GI flap holster.
To prevent rust, get some Johnson's Pate Wax and a toothbrush, and wax that baby down. Make sure to remove the grips and wax that area.
Then wipe it down with a T shirt rag to get all the wax off.
It works in the Oregon rains. Wax that holster too, inside and out.