I no longer have a K10, but had one with an adjustable objective for parallax correction. Pretty good scope, even by today's standards. Have no idea when it was made, but I'd guess the '60s.

Regarding old .222 brass... I was given several hundred rounds a few years ago, some of it may have been unfired, but all of it, Winchester and Remington, was probably from the '60s. Some of the Winchester brass was at least ten percent lighter in weigh than the newest Winchester brass I have which is probably ten years old. This is a significant amount and required a powder charge adjustment (upwards) in the lighter case to get the same velocity as brass I was already using.

The old Remington brass was also lighter, but the discrepancy wasn't nearly as great as with the Winchester cases. Still worth checking out if you run across older brass.