just speculating........
in the 1000 meter matches
is the long barrel more to maintain supersinic velocities?
accuracy means different things to different people
does barrel length help determine accuracy?
to me that means group size with barrel screwed into a machine mounded reciever
to some it may mean open sighted bullseye one handed handgun shooting
in a scoped RIFLE and a sporter or light weight....or even a t/c or similar handgun
ALL OTHER THINGS BEING EQUAL
the shorter barrel will be more accurate.......MOST OF THE TIME....not ALWAYS
simply because of the rigidity
don't forget harmonics.....1/4 inch either way will have an affect....not relative to OP
http://www.shootingsoftware.com/barrel.htm this was very interesting
not purely accuracy.....but the bullet exits the barrel sooner minimizing shooter error
.............longer barrel has less blast........minimizing flinch
.............longer barrels have more velocity...minimizing range estimation