Without the gun in our hands to inspect, no one here truly knows wether or not this gun is really new and unfired (except of course for the normal test shots - usually in every other charge hole). I'm sure there are and will be guns (as well as many other goods sold) that were represented as new but are not in actuality. While I doubt the factory would insert shims to fix end-shake, we don't actually know who put them in. It could have been the Dealers GS that simply figured he'd throw a shim or two in rather than go through the hassle of sending the gun back to the factory. Maybe the end-shake was picked up prior to sale & maybe it wasn't. Maybe another customer looking at said gun picked up on it and someone just put a few shims in to be able to quickly sell the product. We will never know. I do know one thing, sometimes even factory's "fix" things the easy way but again, we can't say that for sure as none here truly know.
That said, if the new owner objects to owning a "new" gun that has already been repaired (and not disclosed), he should ask for his money back. Unfortunately, the warranty might have been voided by disassembling the cylinder but I am not an attorney. Maybe the new owner himself inserted the shims - we simply don't know. If I bought what I believed to be a new gun (or anything else for that mater) and it had been repaired and undisclosed, I'd be mad & upset and demand my money back.
The warranty card being blank and still in the box means nothing! I have many guns that are 30,40 50+ years old that I have shot many many times and the warranty card is still in the box and not filled out!