Here is my Glock 21 barrel after 125 rounds of mixed manufacture ammo.
Hard to believe but it is true. The secret is it was cleaned/treated with Archoil AR4200 before I shot it. You can see some of the barrel is still shiny. The Archoil CLP was not burned off by the powder heat and pressure.
So far I do like the Archoil AR4200 CLP. I’m still testing it though.