The longer barrel does not promote accuracy, in fact a shorter barrel will be more accurate at shorter ranges than a longer barrel because there is better harmonics in a shorter barrel and also because the bullet does not spend as much time in a short barrel as it does in a longer one.
Well I see the smoke and mirrors are active
accuracy depends on the bullet leaving the muzzle at the same time so a low extreme spread of velocity as it means that the bullet will leave at the same point in the sine wave. Now if that departure time happens with the barrel being at the top or bottom of the wave accuracy is very good however if it leaves in the middle the spread will be more as at the ends of it's travel the barrel is momentarily staionary unlike the middle part where it's still moving.
Long barrels were and still are used in Target rifle shooting as with the Aperture sights it provides a longer sight radius, of course using a scope negates this
. I believe that the thoughts on short barrels come form the benchrest shooters who use extreme bull barrels and have to shorten them to make the class weight. Also the cartridges used are designed for small charges of powder as after all most bench shooting is conducted at short range. Notice that the long range bench shooters tend to use longer cartridges. not because they are more efficient but because the small PPC type cartridges cannot supply the velocity required for long range shooting.
As an example one guy at the gunclub I used to belong to had a custom bench type rifle built by Callum Fergerson then decided it would be good for deer. To get it legal for deer he had to overload the cartridge which was 6mm PPC or 6mm BR so much that first firings expanding the primer pockets
so to get more than one firing he GLUED the primers in
and thought it was clever. 1700 ftlbs of muzzle energy are required by law for deer shooting here in the UK.
