Blame bench-resters for shortening bbls....
The harmonic "wavefront" that propagates down a bbl w/bullet passage gets exponentially greater w/bbl length. For example: a 16" bbl of equal diameter to a 26" bbl will provide much less harmonic distortion to the bullet's passage and, therefore, less movement at the muzzle....
The inverse is also true, i.e., a bbl of MUCH LIGHTER WEIGHT but shorter length can be made that reproduces the (acceptable?) harmonics inherent in a sporter-weight bbl....
I've shot "a quick five" many times from my Ruger 77 .308 Mountain rifle that I've shortened to 17" - the "group walking" happens at the bench, to the tune of a .65" group becomes 1.2" between shots 2 and 5....
Pigs, however, only complain that the group NEVER goes beyond "one-minute-of-pig" out to 400yds. The longest string I've fired was 14 shots - 11 pigs down, with 2 "finishers" for the two that got out to 400yds. FWIW....