What is run out??

[burntmuch]

I know this seems as a stupid question. I cant find the answer. Is it the tension on the bullet from the neck of the case?

[Castaway]

No, it's not tension, it's a measure of how concentric your loaded cartridge is.  Imagine laying a loaded cartridge on a glass table, bullet pointing towards  you.  As you roll the cartridge, look closely at the tip of the bullet.  It will go in circles.  A measure of this is the run out.

[burntmuch]

So its referring to how straight the bullet is in relationship to the bore??

[Castaway]

Exactly.

[burntmuch]

Thank you sir

[Castaway]

If you get 0.003" run out you're doing match quality ammo.  It can be minimized by good dies and or by partially seating a bullet, turning the cartridge 1/3 of the way, seating a little more, turn again and do it the 3rd time.  Not really sure this helps, but it makes me feel better with rifle cartridges.  For pistol I don't worry about it.

[AtlLaw]

If you get 0.003" run out you're doing match quality ammo.  It can be minimized by good dies and or by partially seating a bullet, turning the cartridge 1/3 of the way, seating a little more, turn again and do it the 3rd time.  Not really sure this helps, but it makes me feel better with rifle cartridges.  For pistol I don't worry about it.

+1