Wow! I learn something new every day. I didn't realize the 512 went that far back. Thanks. Mine being an x has slightly different sights and is from '70.
You have a nice pair of .22 rifles there.
A short 512 story: In the early '70s a friend and I tacked up a target at fifty yds with the tack in the dead center of the bullseye. The idea was to pit his 10/22 against my 512x as to which was the "tack-driver". He shot first and struck just to the right by about a half inch. With my shot the target drifted to the ground. Upon inspection the tack had been "tacked". Game over.
BTW: Both shots fired off-hand from kneeling position.