i wish people would quit saying "casting." there's no "casting" involved in Colt receiver manufacturing. what you're looking at is called "forge flash."
as far as fit and finish- i don't know what to tell you. LMT, for instance, as some may recall me commenting on many many times before, does SHIT finish machining compared to other manufacturers. when you buy an LMT, you expect shitty finish machining. you expect forge flash and tool marks and even gashes and scrapes and dents and so forth. you don't buy LMTs for finish- period.
i dont have that much experience with colt, but from what i've seen/read, they're basically the same. if you're buying them for finish, you're kinda dumb- cause that's not what they're about.

