Duplicate post from barrel forum:
I bore scoped a Ruger OEM tapered barrel on video. The barrel is dirty and it is used for experimentation and practicing technique e.g., lapping.
One thing that I think keeps this bore scope from being a "10" is the light. I adjusted the light as low as it will go and it still casts a hot spot of light in the center of the frame. I will try to experiment with some schemes to diffuse the light e.g., micro diffuser ring of white plastic or coating the LED ring with something. For the time being I've altered the video with an Adobe video editor.
For your entertainment. The carbon ring(17 seconds) as well as normal deposits are visible. There is a significant lead deposit ~"1" from the muzzle which would be something I would red flag if I cared about this barrel. There are readily visible machining marks along the bore but macro photography tends to make machining marks look worse than they are in my experience. Notice the machining marks are not collecting lead like the anomaly near the muzzle.