I bought a used SCAR 16 and I was inspecting the bolt and barrel. The bolt seems to have a indented circle on it. Is this a sign of excessive round count? How many rounds approx would you guess this rifle would have to have to have this happen? Is it time to replace this bolt? The guy I bought it from is offering to take it back and buy it for what I paid. What would you do? I spent about $2,500 in total for the Scar 16, has the Geiselle trigger upgrade. I could buy a new one for about $2,700.