As an engineer/scientist/physicist I'm contemplating the impact of neck-sizing only (NSO) vs FL sizing on the flight of the projectile. Without delving into calculations, intuitively, the two largest factors for accuracy would be the barrel vibration (whipping) and the terminal force imparted on the back of the bullet as it leaves the muzzle. Bullet rotation and geometry also have an effect, but I'm assuming that is a constant while addressing sizing method. It's impossible, but let's also assume a perfect muzzle crown and bullet base interaction which pushes on the bullet perfectly concentrically. As the bullet leaves the muzzle it has no history of how the case was resized except for how it affects the "tuning" to the barrel and subsequent vibration (and harmonics), which, on a microscopic level causes the barrel to 'point' in a different direction. This might be the key: the more constant pressures from the NSO cases required to expand less into their mated chambers. FL sized cases allow for more variability at the beginning of the pressure curve. Even if it's insignificant, I would still NSO to increase case life. A ridiculously thick barrel would solve all the problems of any influence on vibrations.