That is outstanding accuracy, not common in that model, even from Knights armament, 600 - 800 yes, that is a keeper no doubt.
Be very happy my friend.

I will also mention, shooting 12" plates at 1,000 yrds, takes skill as well, unless it is a perfect day, many things come into play, wind, mirage, that don't make a hoot at 300, make monumental differences at 1,000.
Congratulations.