Just wanted to give an update:
I found this on amazon with a 5.5 mm head,

http://www.amazon.com/GCA-Waterproof.../dp/B00N4L5N4A

works REALLY well for looking inside barrels,
I scoped my 7mag browning bar and saw a whole bunch of copper closer to the chamber.
For $19 I paid for it, it rocks.
The rifling is easy to see.
I have not tried to shove it down a 223 but in theory it should fit.