The desirable direction of view will vary depending on the object you’re using the borescope for, for example, a 90° Mirror Tube is ideal for a gun or rifle barrel, while a 0° direction-of-view is preferable if the subject is ahead of an entry hole. ...
The camera rod of my Lyman borescope is too large in diameter for .17-caliber barrels, so for three of the test rifles I relied on cleaning patches wet with copper solvent to detect the presence of metal fouling. The barrels of the Ruger Model 77/17H and the Remington XP-100 had accum...