Some of you may already have one for looking at your cylinders through the spark plug hole. I recently came across the need to look down a pipe to discover why it kept clogging. Went to Harbor Freight and looked at the endoscope/fiber optic camera they had. Two choices: $99 and $199, both with big, fat camera heads. My experience buying stuff from Harbor Freight is a 50:50 proposition. Half the time it works, half the time it's crap. At the register, they told me "there's a restocking fee on the camera if you return it." Wilco Tango Foxtrot? Um, I'll wait. Went home and started searching. Came up with dozens of options on Ebay. While searching, I'm seeing I can find all sorts of head diameter options, so of course I think of using the same thing for examining my barrels. I settled on two, the first one being a 5.5mm Fiber Optic USB camera, 640 x 480 resolution with a 1m armored flexible fiber. $34, stocked here in the US. It arrived the 24th. The second one is a 8.5mm fiber head, with much higher resolution, 720p HD. On its way via China Parcel Post (i.e. 3 weeks). It was also $34. Setting it up was a snap, sort of. Out of the box, I plugged it into the laptop I usually use. Windows couldn't load the drivers for it, but on that beast it's a problem with Win7. I plugged it into an older Dell Win7 machine, it worked great. What surprised me was how easy it was to use it on my tablet. Downloaded and installed CameraFi off Google Play, plugged the camera into the OTG cable, and Viola!, I'm looking down the borescope. BONUS! (An OTG cable is a male/female adapter that you plug into the tablet/phone micro usb port that allows you to plug in usb devices like a thumb drive.) The first thing I checked out was the chamber and barrel of my new (used) CZ550. Everything looked good. I could see copper fouling still in spots in rifling of the barrel. Sorry, I didn't think to take pictures here. Next was my .308. Looking down both guns from both ends, what surprised me was how the chamber reaming on the 308 looked rough compared to the CZ550. When ordering the camera, I deliberately chose one with a 5.5mm head, thinking it would fit down my AR15 barrel. Nope. While the major ID is 5.56, the minor ID is less. D'oh! So it wouldn't fit down my German AK22. Then I looked inside some 308 cases. The rifling pictures attached aren't of the greatest quality. The head as a focal range of 1-5cm, and it seems to work best in when the object is ~2cm away. If I held the camera right, there would be much more contrast and definition between the lands and grooves. I'm pleased. For $43 all in, I have an extremely useful visualization tool. No more pulling out the multitude of dental mirrors that I have in my tool box. I can hear it now, "Honey, will you go grab me my borescope please?" followed by "What's a borescope?" Pictures attached.