One of the internets best known custom air rifle builders in North America is Mr. G. Barnes. Mr. Barnes
builds incredible air rifles that are destined to become saught after collectibles. His attention to
detail and workmanship are second to none.
Another air rifle builder, Dennis Quackenbush, builds very accurate rifles. Although different
from Barnes, his rifles are well built and many good reviews on the internet. There is a lot
of information in his web site as well. Good articles on airgun barrels, machining, etc.