I just bought a NIB Glock 21 Short Frame, I took it to the range the other day and shot 50 to 60 rounds through it. When I got home and field stripped it to clean it, I noticed markings on the barrel that werent there before. They looked like wear marks from the slide. Im wondering if this was caused by not putting enough lubrication on the outside of the barrel, or if possibly my recoil spring popped out of place or something. Im not totally sure, I did shoot a couple of Federal Hydra Shocks and a couple of Gold Dot +P rounds through it. Im just trying to figure out if this is a minor problem such as not enough lube or the +p rounds, or a major problem with the weapon. Advice would be greatly appreciated.