Well, if it's just the finishing, I'm really not concerned with it. I bought it to be shot, not to be a safe-queen. I only put 100 rounds through it myself, the previous owner put 200 through it, and it was that way when I received it, I just never really took a close look at it before we went into my LGS to do the transfer. I just wanted to make sure it wasn't something more serious. If the finish isn't "supposed" to wear out like that, but it still functions flawlessly and something more serious isn't going on, i can live with a worn finish, lol.
I'm sorry, man. I swear I'm not laughing at you, but you got SERIOUSLY scammed. Whoever lied to you, and sold you that gun, go whip his ass. First, let me make it clear that nothing's wrong with the gun. But that jerk straight LIED to your face. I have a G21SF with over 6,000 rounds, and it has almost zero wear on the barrel. Maybe the guy just ran it dry, but I would guess that gun has at least 5,000 rounds through it. Maybe it was just fired dry and with grit in it, but that's a LOT of FINISH wear.
After all the lying is done, it really doesn't matter. I would be pissed about the guy lying to me, but it doesn't really matter. Nothing's wrong with the gun. Luckily, it's a Glock, and it will last for many more tens of thousands of rounds. Just know that you CANNOT trust that guy. He is a liar. Don't buy from him again. By the way, could you post some pictures of the whole gun?
Here is a picture of my G21SF at about 6,100 rounds. It's not the best shot of the barrel, but you can see it. I keep my barrel and muzzle opening well lubed, so there's little wear. I'm guessing the previous owner just didn't lube the barrel. It's still a good gun.