I took gunsmithing class in building double rifles on shotgun actions from E. Brown prior to his writing his book on same subject, and I have built numerous double rifles using his system, without a problem. Naturally, some people with little or no experience should attempt to take on such an activity. I took antique clock repair classes from one of the best antique clock repairmen in this country, and he told us that some people should not work on anything more mechanically complex than a paper clip, and through the years, I have found his assessment to be sooo correct. I think this rule applies to building double rifles on shotgun actions too.