Can the custom gun or rifle be legitimately regarded as a form of art? I believe it can, and presently, I state my case.
The custom gun or rifle demonstrates the maker's mastery of his craft, his ability to move steel and wood to create an object that is not only functional but aesthetically pleasing as well. Much like a handmade watch or a piece of handmade furniture, one can appreciate not only its function, but also the craftsmanship that is wrought upon every piece that makes up the whole. That is not to say that it is just an assemblage of well made parts, for the truly custom gun must be of a unified design. It must be aesthetically pleasing as a whole, with no single aspect of it standing out from the rest. It should be as pleasing visually as it is functionally and ergonomically. Sleekness of line is of little value if it does not comfortably fit the user or perform to expectations. Acceptable accuracy and reliability without pleasing form can be had in an "off the rack" rifle. Extreme accuracy at he expense of all else can be found in the custom rifles built for benchrest competition, and while bench rest rifles could be regarded as a sort of "industrial art", that isn't the art form that is the present subject. Much time and treasure is spent on optimizing the ergonomics and reliability of military rifles but they can hardly be regarded as art, even though they are capable of evoking a wide range of emotional responses from those who see them. Military rifles also fall into the category of weapons, which the custom sporting gun or rifle most certainly is not.
The custom gun is an expression of the maker's imagination as well as his ability to work with the media of metal and wood. This is most evident in the completely unique, hand made gun. Much like the sculptor who sees the statue inside the block of marble, the gunmaker sees each part inside the block of steel or wood. Unlike the sculptor's single piece though, the gunmaker's many pieces must all fit together and function as many interrelated mechanisms, for guns can be (and often are) quite mechanically complex. Each of these parts in a truly high quality custom gun must be fit with precision and finished to the highest standards, and much like the highest quality timepieces, this work is done by hand. Beside having mastery of the physical tools of his trade, the gunmaker/artist must also have almost encyclopedic knowledge of the materials with which he works. The proper steels from which the varied parts are to be made demand a knowledge of metallurgy, heat treatment, welding, soldering and brazing. Knowledge of the characteristics of the various species of wood with which the gun is stocked is also a necessity, as well as the various finishing processes for each material. As arduous as this work is, it often pales in comparison to the design work that precedes it, and that is where the gunmaker/artist can allow his imagination to take flight, to come up with something unique, aesthetically and functionally. The satisfaction of creating something that had literally not existed prior, of taking formless raw material and through seemingly countless hours of labor and inevitable setbacks, conjuring something that is equal parts sculpture and tool, is difficult to convey. There is, almost literally, a piece of the gunmaker in every one of his creations, for it is a mentally, physically and emotionally draining process. Luckily, there are those who can appreciate this, people who desire to posses something unique, not as a "status symbol" but simply for the pleasure they derive from it. I am very grateful for those patrons, regardless of whom they choose to patronize.
Often, even those individuals who would not consider themselves "gun people" will appreciate the shapes, the forms, the craftsmanship and details of a custom gun. They can appreciate the harmony and balance in its design, the textures of the different surfaces and finishes and they can wonder about the time, effort and methods that went into its creation.
Yes, I think that a custom gun definitely qualifies as art.
I purposely did not mention engraving because although it is frequently used as embellishment on guns, I believe it to be an art form unto itself. I also believe that not all custom guns need such embellishment because the handmade custom gun, much like the handmade timepiece, can stand on its own aesthetic merits.