It's an Anderson 556 NATO carbine barrel. I'm finding that some of my boolits have grown a little and when sized the step down to the nose on the NOE boolit is erased. If I try to put the nose into the business end of the barrel they won't drop in where as some of my other boolits from same mold cast from the same alloy (mixed 20# in a pot and poured off into bigots) will drop in to the barrel all the way to the driving band.
Will add that some have been water dropped from mold, heat treated, or powder coated. Rather frustrating and I'm on the verge of going back to the Lee c225-55-fn boolit and enjoying the decent accuracy I've reached there.