How much runout to affect accuracy?

[kenfa03]

Just curious. My Lee .270 full length die is giving me anywhere from .010-.025". With some so bad they won't chamber. Just ordered a RCBS to replace it.

[rg1]

What I've read over the years about runout: Less than .005" for hunting type rounds and less than .002" for target-match loads. Loaded rounds measured on the ogive of the bullet.
Here's a recent discussion on another reloading forum about controlling runout:
http://www.thehighroad.org/showthread.php?t=470100

[Unclenick]

He must be talking about case neck runout since it's in connection with the sizing die rather than the seater?

Lee sizing dies are honed, so they should be round and concentric. It seems to me more likely the expander is pulling the neck off axis. You can test this idea running a few cases in without the expander present. It those have runout worse than before you size them (measure both), then the die should be sent back for replacement. If removing the expander fixes it, then get a variable speed drill, chuck the expander in it and polish it up with crocus cloth. Try to set it up so it starts to expand the neck at the shoulder junction when the second half of the case neck is still in the sizing die. That helps the neck start back straighter. Just don't get them so close they bind. Be sure to use a good neck lube.

To address your original question, runout error in .30-06 match ammo was once measured that showed up to a bout one MOA of group size increase, IIRC, from 0.004" runout. More runout didn't seem to make it any worse because apparently the bullet could straighten itself out in the bore enough to be no worse than that. This would be with jacketed boattail bullets about the size of the 175 grain Sierra MatchKings. Lead bullets will swage into the bore at an angle and show much worse effects.