The British gun trade was built on a foundation of apprentices. If you had to wait until you were a master gunsmith before being employed by Holland's, Purdey's, Boss, or whomever, then none of these firms would still be in business. I don't know what qualifications are needed to be accepted as an apprentice, but there are a lot of young smiths at these old venerable firms, and surely they didn't all start out as experts. I know an English smith that immigrated to Canada, and he had on display in his shop a flintlock (just the lock) that he had to build up from scratch as part of his apprenticeship.