Wasn't meant as an insult, but these big-cased rifles are hardly a nice introduction to someone who's a "6mmShooter".
Nice to see you've done your homework ... and are experianced.
In our part of the world, a 30-378 Mark V Accumark is just a little over
$ 2,000 retail, + tax, so Yup, your "used" for 60 rounds price looks O.K.,
all considered.