Once again no clue what I'm looking at!
Teslong scopes come with a 45* screw-on mirror, giving you a 90* look at the lands / grooves. That's what Csbc4fun's pics show.
BTW, focus can be adjusted by screwing the mirror in/out for the barrel diameter. I bet his pics could be sharper with some trial & error focus adjustment as the Teslong is capable of very sharp images.
Get a teslong scope, plug it into a USB port on your Windows desktop/laptop or Android tablet / phone. If you're in the Apple world you'll need the WiFi version (+$25-30).
If you have a Windows computer I'd start there - the scope will likely be automatically recognized as a camera & put a picture on the screen without any add'l software.
Android requires getting an app from the Google Play store. The one that works for me is USB Camera Pro by ShenYao China. Several similarly named apps on the store; get this one - it works & isn't full of ads.
Put your rifle in a bench vice, pull the bolt - or lock it back on a semi-auto - and stick the scope end thru the chamber & into the bore. If the pic is fuzzy, pull it out & twist the mirror 1/4-1/2 a turn & try again. If the image is worse, pull it out & twist the other way....
You can wipe the mirror with a clean, dry cotton swab if it gets dust, a fingerprint, etc. on it. Lightly, it's a front-surface mirror - the silver is on top of the glass instead of behind it.
Move it up & down the bore. You'll see the lands 'twist' as the scope is moving in a straight line. Turn it carefully - I'm on my 2d one - I stepped on the fiber optic portion on my first & broke it.
WOULD NOT DO WITHOUT IT NOW. You can see chamber condition / markings, the beginning of the lands, carbon / copper in the barrel, etc. Examine gas ports for alignment with the gas block & smoothness (or lack of) the port opening in the barrel.
Check the muzzle for sharp edges (or lack of). A recently-acquired 18" AR heavy barrel revealed an _atrocious_ crown. Removed the brake & 15 mins with a brass screw in my hand held drill + valve grinding compound made a world of improvement.
Ya gotta look at your own guns to get an idea what you're looking at / seeing. It ain't rocket surgery ;~) Jump in and do it & you'll learn how good / bad is your cleaning routine, whether a given barrel is building a carbon ring ahead of the chamber, whether or not fire-cracking is developing, etc.
Much of this is learned by comparing images from multiple firearms with more or fewer rounds down the tube and so on. It's edumacational!
We're never too old to learn (I'm 73). Learnin' new stuff helps keep our brains from petrifying. Go for it!