I'm going to play devils advocate. I own a Hawkeye borescope and I have no complaints about how well it functions.
But how much does inspecting a rifle barrel with a borescope tell you? From my experience Shooting a rife carefully for accuracy is a far better indicator of a good or bad barrel than looking with a borescope. I've seen barrels which look very ugly which shoot quite well and the reverse. Certainly a borescope is good for showing a shot out throat, or a chamber which wasn't cut concentric with the bore, but the reality is that if a barrel shoots well there is no no reason to check it with a borescope. At best it will just make you worry. I've only had a couple of cases where having a borescope led me to make a bad shooing barrel shoot better. Those had severe copper fouling which responded to more aggressive cleaning. More careful cleaning would likely have fixed it without the borescope.
I've replaced several bad shooting barrels with new ones from respected manufacturers (Hart, Pac-Nor, & Shillen ) and they invariably shot much better. Some of the old barrels showed problems with the borescope, some did not, but shooting badly was always the deciding factor.
My Hawkeye borescope has more than paid for itself, but from working on engines and generators, not guns.