Gosh, you would think Leupold would know better after the hundreds of thousands of scopes they have made and what shooters want and NEED in a scope....honest windage and elevation adjustments and HOLD POI. Geesh!!!!!!My new VX-5 has held up good on my 280AI,and I tuned up a fairly light 300 Weatherby Magnum for a customer.It's a VX6,and it held its zero better than I did on that thumper.I the the newer ones are doing pretty well.I had to send one of my Mark 4's back last fall because it wouldn't hold zero,but it's common for them to do that.Something to do with a plastic part that is put in them when they're built,but is replaced with a metal part when the plastic one fails.