As a generality, modern rifles are built with far better machinery than those of the "way back when" and commonly will shoot tighter groups. Milsurps may well be stronger from the standpoint of rough handling--which few people do.
Sort of a tossup. Old milsurps can be made to shoot quite accurately, particularly if sporterized via stock and sights.
You're from BATFE? Come right in! I use all your fine products!