I think it is a combination of factors: First, time. Martini & Hagn is a small shop and the time needed to turn out a complete rifle (action, barrel, stock work, etc) is far more time consuming than the time taken to turn out an action. I assume the action itself is the work of one craftsman while the stock and the 'actioner' role is filled by others. That would allow more actions to be completed than complete rifles. Second, some like the work of a particular stockmaker, such as Steve Dodd Hughes, an acknowledged master in wood. He doesn't build his own actions, so the superb Hagn action would be a natural for a custom built rifle, just as I assume the original owner of my Jack Haugh wanted to have him stock and engrave it while recognizing that he did not build his own actions or that he simply wanted a Hagn action done in a Haugh built single shot. Same situation in a H&W stocked and completed rifle using that shop's single shot action of choice, a Hagn. Dave