I don’t think so. Sierra gets the same accuracy with their bullets in today’s barrels as they did back in the 1960's in barrels made then.. Benchrest groups are still under 2/10th MOA at 100, 3/10ths at 200, 4/10ths at 300, 5/10ths at 600 and 6/10ths at 1000. The average group sizes are smaller and those tiny record ones are the result of all the rifle and ammo variables being at zero or cancelling each other out. There’s no way to tell which one made them so tiny, but the odds are in favor of cancelling them out. Recently, the average benchrest group sizes got smaller when they quit neck sizing their fired cases and properly full length sized them. That made their largest groups somewhat smaller; increased the odds of getting a very tiny one that sets a record.
Better jacket material available these days as enabled smaller caliber bullets to be longer and heavier with the same accuracy levels as shorter, lighter ones. Good examples are with bullets used in long range matches. It wasn’t until the late 1980's that 28 caliber, long and heavy match bullets shot as accurate as the 30 caliber ones. That was followed a few years later when 26 caliber ones came out, then later 24 caliber ones. Lighter bullets mean less bore axis displacement variables while they go through the barrel; one big reason why 24 caliber bullets are popular in 1000-yard bench rest matches. But their average accuracy down range is not much better than larger caliber ones. They all shoot somewhere under 6 inches at 1000 yards.