Normally I'm very careful about following the rule that produces are usually not worth what you pay for them but this piqued my interest.
2M 6-LED 5.5mm Lens IP67 Waterproof Android Video Endoscope Borescope Snake USB Inspection Camera
I figured at that price I could afford to gamble. Well, I was surprised. It took a while for the small bubble wrap envelope to arrive but when it did and I got a camera viewing program up and running on my PC the images I got more than exceeded my expectations.
There are other sized units in both length and diameter however the 5.5 mm camera will, quite easily, fit down a .22 cal pistol barrel.
The guns that I had close at hand as I sit here this morning at my computer are my 30 year old 1911 that was my EDC for years and a Buckmark .22lr pistol with a Tactical Solutions 10 inch barrel.
So here are the pics that I just quickly grabbed from my monitor.
Note: the software I'm currently using only produces 640x480 images. The camera documentation says that with a PC 1280x720 is possible.
About half the barrel and bolt face of the 30 year old 1911:
The bolt face and chamber of the Buckmark .22:
The view from near the muzzle of the 10 inch .22 cal barrel:
IMHO not bad for an investment of less than $20.
