If a shooter is able to consistently hit the target then he's accomplished; however, there's more: If a shooter actually UNDERSTANDS his craft as well as the weapons he uses, AND knows how to explain both his skill and weapons to others in such a way that they readily understand his explanations then he is, demonstrably, accomplished.
In order to be recognized as an accomplished shooter a certain amount of either physical or intellectual evidence is necessary; i.e., peer group recognition evidenced by: trophies, certificates, credentials, punctured targets, or even a history of dead or wounded adversaries.
Jerry Miculek is an accomplished shooter; and he has a history of personal awards, prizes, professional wins, and video evidence to prove it. Wild Bill Hickok was, also accomplished; and he had the personal reputation, and dead bodies to qualify him as being an accomplished shooter, too. Simply stated, if a shooter is accomplished then his shooting skills are both demonstrable, AND repeatable at will - His will.
(Hope this helps!)