This short action magazine box is an original Winchester part for use with "short cartridge" rifles (.243, .257, .308, .358, etc.). We're not sure what happened to this box, but it looks like someone tried the move the baffle, and then didn't. This box is fully functional, it just has a couple of extra slots in it.
We use the NRA Modern Gun Condition Standards Grading System for grading part conditions. You can read about it HERE