I recently bought an Olympic Arms AR-15 and have a few questions about it. First, what is the quality of Oly arms ARs, and how do they compare with other ARs such as Bushmaster, Armalite, etc. Second, how can I tell who manufactured my upper? There are no barrel stampings as far as I can see. I have taken off the handguard and cleaned off the front of the barrel. Still no markings. It is an A2 upper. Third, how should I go about cleaning the gun. Never cleaned an AR before and the upper looks pretty dirty. Also, since...