I have always wanted a borescope but always bought a new gun or barrel instead, six months ago I bought a borescope but never used it except for one barrel.
Last Friday after work I had a quest to look at as many of my barrels over the weekend as I could. First one I cleaned but made the mistake of oiling after ward.......2" down the barrel no vision !!!!!!!!!! clean the barrel and DRY patch, bore must be dry !!!!!!!! First barrel I knew was toast was a 6-284 1-8" Pac-Nor 3 groove. WOW first 5" ahead of chamber was dry lake bed with no sign of lands and grooves. was fire cracked beyond that to around 9".
Second barrel was the first Varmint rifle I ever owned, A Winchester Heavy Varmint in 220 Swift (factory barrel), I was stunned this barrel has pushing over 2000 rounds and still looks pretty good, firecracked just a bit but not bad. accuracy is still awesome but bullet must be seated out so far that magazine is not an option.
Third barrel was a 223 bolt action with a documented 750 rounds down the barrel, no cracking and very little wear.
Fourth barrel was a 1-14" twist 22-250AI Pac-Nor 3 groove, barrel is absolutely toast for first 3" with around 1000 rounds fired.
Fifth barrel is a 300WM with a Shilen barrel, 400 to 450 rounds fired, firecracked in the free bore area but once lands start is very pristine.
20th barrel 222 Remington 1-14" twist 3 groove Pac-Nor, documented 1200 rounds fired. first 2" of barrel toast completely firecracked.
from 20 barrels of my own rifles I had factory from Winchester, Browning, Remington, Sako,and CZ. for custom barrels I have Krieger, Bartlein, Shilen and Pac-Nor. Of the 20 barrels I have looked at only 3 are completely toast and all three are Pac-Nor 3 groove barrels. Don't know if it is inferior metallurgy or because the lands are wider than any other on the market??????? A 222 Remington custom barrel should last as long as a factory barrel IMO, but to not even come close is unacceptable.