The author using the Hawkeye to examine, in magnified detail, the inner walls of his rifle bore.

About 10 years ago, outdoor writer Jim Carmichel showed up at a prairie dog shoot in South Dakota with a truckload of rifles and a very interesting instrument that looked like something from the space program.

It was a long, thin, stainless steel tube attached to several cables with an eyepiece and a television monitor. It had a built-in lighting system and various optical attachments as well. Its purpose was to study--up close and in magnified detail--the interior of a rifle's barrel.

For the next two days we were torn between shooting prairie dogs and studying grooves, lands, corrosion and fouling through Jim's optical marvel.

The single aspect that really stands out in my mind was our steady destruction (all in the interests of science, of course) of the bore of a brand-new .220 Swift. The rifle was fresh off the rack when we arrived. For two days we shoved box after box of hot factory ammunition through it, and it was questionable which suffered the most, the prairie dogs or the rifle.

Each night we would put the long tube of the borescope into the barrel through the chamber and study how the steel was being gobbled away by hot loads in an already-sizzling bore.

It was, truly, a revelation--not only in terms of what a steady diet of red-hot ammunition will do to steel but also of the valuable information that can be gathered by a serious scientific instrument like a borescope.

The first mention I can find of such a piece of equipment is in the 1978 Gun Digest in which A.M. Wynne wrote about a borescope made by a company called Willrich. Because of the limitations of conventional photography at the time, he was unable to produce any actual images of the bore itself taken through the scope (although he did describe, in detail, what he saw through it in the study of two dozen different rifles).

The scope itself was a modification of the device doctors use to look in your eyes and ears. It had a long tube that projected light down into the bore and a system of mirrors that projected the image back to the optical eyepiece. The lighting system required a battery pack with cables.

Today the serious rifle nut who really wants to study his bore can do so much more easily, and with considerably more technical sophistication, using the Hawkeye Borescope from the Gradient Lens Corporation of Rochester, New York (home of Kodak and the optical capital of America).

The Hawkeye was the brainchild of Gradient's chief engineer. At the time, the company was involved in consulting on several defense projects, and the engineer (a devoted rifle shooter) concluded that some of the equipment they were using could be adapted for use on his favorite subjects. The resulting product was successful enough that today the Hawkeye Borescope is the sole product of Gradient Lens, an independent small company with about 15 employees.

The Hawkeye Borescope with right-angle viewing lens.

The Hawkeye is considerably simpler than either Wynne's borescope from the 1970s or Jim Carmichel's from 1996. The basic model consists of two stainless steel tubes of slightly different diameters, one of which slides over the other. Light is projected down one tube and reflected back to the eyepiece through the second. By rotating the outer tube, you can get a 360-degree view of a bore or follow one groove or land as it rotates as you pull the borescope out of the bore.

The eyepiece is similar to the familiar medical instrument, but Gradient goes one better and also offers a right-angle adapter to allow more comfortable viewing. Light is provided by a small flashlight that screws into the eyepiece and also serves as a handle. With no battery pack or cables and no television monitor, the whole outfit packs into a handy little carrying case that can easily be taken to gun shows, gunshops or anywhere else you might want to look at the bore of a rifle.

The Hawkeye does not end there, though, and right away it should be pointed out that it is not cheap. The standard instrument with right-angle eyepiece, which I have, sells as a package for $995. This model has a 17-inch tube, with an outside diameter of .188 inch--small enough for a .20-caliber bore but not a .177. The 17-inch length allows you to examine up to a 34-inch barrel, assuming you have access from both ends.