Just because you have never dropped a mag, with a used weapon you can't be sure who owned it & how it was treated. I would buy a new magazine (hey, at the very worst you will have a new one to use & compare) and see how things work. The WWB ammo does have a lot of QC issues, but this sounds more like a feeding problem than anything else & the weak link here is likely a magazine. The weapon is probably fine, and someone was using the mags to do quick changes on a hard pavement or surface. The USP 40 should run many thousands of rounds without a problem, but magazines are sometimes hard to see a change in. Just my 2 cents worth...