I had an occasional flier from one of my barrels last winter that had always been brilliant, pulling it through didn't sort it, but scrubbing it with a brass brush and then pulling it through again got loads more muck out and it was back to being great again, must have had some debris in the grooves that a pull through could not shift.
if you try this make sure the brush is brass bristled as this is soft and will not scratch the bore and not coated steel, touch the bristles on a grind stone, if it sparks it is not brass!
Coincidently this barrel has always preferred 4.51's too although it is a barley twist not a Protarget.
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.