I was looking through a tool catalogue and noticed a 10mm inspection scope selling for $100 odd, so I figured there might be something smaller online that would fit into the smaller caliber rifles. The best "reasonably cheap" $220 borescope I could find was 4.5mm, any smaller and they are medical endoscopes and prices go over $1k.
What sizes are the borescopes used for inspecting rifle bores? Do they need to travel right through the barrel or can they just be fit to the chamber and muzzle? Do they need to be flexible? Portable as well?
My guess is the former, and yes to flexible as I don't want to be pulling my lever action apart every time I want to make sure it's cleaned well, but I've never ventured down this path before. I would consider one at that price if 4.5mm is a size that will fit 90% of available bore sizes.
Thoughts??