I know I might be coming off as argumentative and I apologize because I don't mean to be at all but as far as accuracy is concerned what else is there besides how tight of a group it shoots? And maybe to clarify a little, I'm not talking about consistent accuracy over time. Simply put if the bullet comes out "traveling to the target at MOA" for lack of a better term will it not maintain that same degree of accuracy no matter the distance?
I'll give this a shot.
Barrel quality and smoothness have an effect on how much damage a projectile sustains while traveling down the barrel.
While a barrel might be able to produce fantastic groups at 100yds, the minor damage to the bullet magnifies the dispersion the longer the range gets.
High quality barrels have smoother lands and grooves, but they are dimensionally way more consistent.
Here goes the golf analagy:
Hit two golf balls exactly the same to 100 yards with your pitching wedge.
One ball is brand new and the other bounced across the parking lot last time you played.
At 100yds, both shots will hit within a reasonable distance of each other. Let's call this <1 MOA.
Now, take those same two balls and hit them 355yds and try to maintain a straight path. The new ball is capable of that. The scratched up one will begin to draw or fade depending on the location of the scratches.
Add in wind effects and altitude, and the dispersion increases. It's no longer < MOA because of the aerodynamics and the resistance created by each golf ball are affected more because of the increased distance and time that it's in the "weather".
Your bullets have a ballistic coefficient. Adding damaged noses from chambering, scratches from the Mag well and striations on the surface due to crappy bore conditions will change the BC for the worse.
Wind affects a bullet at 100yds more than other atmospheric conditions.
Stretch that out to 1k and not only does wind have a much larger effect, but the atmosphere matters even more now.
Throw in a bullet with it's BC that's been fucked up, you now have a recipe for unexplained misses.