Old Rooster, please don't take this the wrong way, as my intent is not to argue, but rather to help folks understand what manufacturers consider when building a product.
I'm a Quality Engineer in Aerospace Manufacturing, and love it when people say, "QC should have caught that!" (I get that a lot, incidentally) The more useful statement would be, "That defect should never have occurred!" But, since it did occur, the Quality Engineer in me would say, "let's make sure that defect never occurs again."
Relying on a Quality Inspector to catch everything that is required, is a fool's errand. I would bet my next paycheck that Burris feels the same way.
Quality Control, particularly in a high production environment, will not catch everything. That's because they select a representative Sample (One out every 20, 50 or 100 scopes, more or less) of overall production to inspect. They just simply will not catch everything, because not everything is 100% inspected. Performing 100% inspection of all product is cost prohibitive and would require a significant increase in the number of inspectors to perform these inspections, thus driving up the cost of the product. Not many people in this forum, or in America for that matter, would support higher prices, which is why so many buy Burris and Vortex in the first place. Cost, and generally, pretty good Quality.
Any Mfr's quality department is focused on Defect prevention. They try to Identify risk in the Manufacturing processes and refine those processes to prevent defects from occurring in the first place. Data used to identify risk is partially derived from customer returns and survey responses, but also from nonconformances detected internally (Defects that never make it to the customer). Trends are identified using that data, and the nonconformances identified that provide the 'Most Bang for the Buck' are addressed first, and usually through manufacturing process improvements.
It gets MUCH deeper than the above, but that's a pretty good 30,000' view of what Manufacturing quality's function is.
I'll get off my Soapbox, and hope the folks here have a better understanding of why defects escape a manufacturer.
JK