One of the most useful and enjoyable tools I have ever bought is a borescope.learned a lot about cleaning and fouling.
Also learned of all the rifles I have ever bought used none were shot out. some rifles such as 220 swift may show more throat erosion than others but can still shoot very well. Some manufacturers rifling is not very sharp and distinct brand new as others. Custom barrels tend to appear less deeply rifled as say a Remington.. none of this is very important as long as they shoot. It seems my Coopers maintain rifling better after thousands of rounds than say a Remington. Just my opinion based on my own limited experience. My borescope is from Innovative Technologies.
www.larrywillis.com. It is self contained handheld including screen and much cheaper than say a Hawkeye. Takes a little while to learn to understand what you are seeing. Looks forward unlike the Hawkeye which looks perpendicular to the bore.
