They all do it. I don't worry about it since it is a shooter. Mine has had a suppressor on it a lot.So I just got back from the range and put 100rds through it. It's accurate as can be both suppressed and unsuppressed. However what is going on with the finish on these damn things? The finish flakes off the threads and shows bare metal and the barrel looks like I have 10,000 rds through it. The barrel hood is showing normal handgun wear but everything else....WTF. I understand the metal is treated at a molecular level but holy cow this is pathetic. I'm calling hk after the holiday.
O and my usp tactical 45 has at least 2,000rds through it and it looks fine. Yeah it has some slight character but the finish wears nice and doesn't flake off like cheap paint!
I'll post pics here tomorrow.