Unclenick mentions:
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As to neck tension, generally speaking, Mr. Guffey has it right: more is better from the starting pressure and ignition standpoint as long as it's consistent. Military match ammo in a number of instances has been found to be more accurate than the same components loaded at home, and that's been traced to the military pitch seal gluing the bullet in and increasing start pressure. Apparently that can be more consistent than neck tension alone.
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And military match ammo in a number of instances has been found to be less accurate than the same components loaded at home, and that's been traced to the military match cases not having a pitch seal gluing the bullet in and increasing start pressure but instead using less neck tension. I've broke down 7.62 NATO match ammo to primed case, powder and bullet, then cleaned out the seal, resized the neck, metered the powder back in and seated the bullet. It shot more accurate than the original stuff when fired in the same rifle.
I don't think the pitch (asphaltum) seal makes the bullet release force more consistant than neck tension alone. Note that M118 ammo's inside neck diameter's a thousandth or two larger than bullet diameter from the mouth back to almost the neck-shoulder junction. It's just barely smaller than bulet diameter there. That clearance allows the sealant to be applied all the way around the bullet during assembly.
Both 7.62 NATO M118 (and 30 caliber M72) aresnal match ammo have a bullet release force spec of at least 40 pounds but no tolerance is mentioned. The spec for muzzle velocity spread is 2550 (2640) +/- 30 fps at 26 yards from a 22 (24) inch barrel. And both have 600 yard accuracy specs of 3.5 inch mean radius average; about 10 inches maximum group size. National Match lots were made with select lots of bullets and primers and produced about 2 inch mean radius or 6 inch maximum group size at 600.
Some lots of arsenal match ammo issued to the service teams were noticably worse than others. They had enough muzzle velocity spread that perfect scores on the 600 yard's 12 inch 10-ring were not possible. And things were worse at 1000 yards. 'Twas common for some team members to carry a Lyman 310 nutcracker tool with a seating die adjusted to set those match bullets back about 5 to 7 thousandths of an inch. That broke the seal and got the bullet release force down to around 10 pounds. Tests of some lots having too much vertical shot stringing showed the bullet release force had a 20 pound (or more) spread about 50 or so pounds. Getting that spread under 5 pounds and down where a lesser force was needed to push the bullet out made them shoot much more accurate and hold better elevation.
The best accuracy I know of shooting handloaded or reloaded ammo in shoulder fired rifles happens when neck tension is as low as possible. As long as the bullet's held well enough to survive normal handling in the shooting environment it's used in that's plenty. Which is why most folks shooting long range matches seat bullets with light neck tension; some of those bullets can be pulled out by hand. And they're seated out long so they're set back a few thousandths by the lands. The force needed to push the bullet into the rifling's much more consistant with this method than trying to control it by neck tension alone.