264 neck bushin sizing to 262

[scalian]

What would cause a 264 bushing to size to 262. My loaded rounds are 265 and i wanted .001 neck tension. I bought .264, .263, and 262 bushing and when I use the 264 it measures out at 262?

 

[CatShooter]

What would cause a 264 bushing to size to 262. My loaded rounds are 265 and i wanted .001 neck tension. I bought .264, .263, and 262 bushing and when I use the 264 it measures out at 262?

If the fired neck is much larger than the sized neck, the brass will overshoot the bushing diameter.

I had many long talks with Patrick Ryan at Redding about this about 10 or 12 years ago, and they finely put something in their catalogue about it.

It happens because the transition is too sharp from the full fired diameter to the sized diameter.

I have modified some bushings to stop this, but it is a pain in the tail to do.

 

[FeMan]

If you are trying to bring the neck diameter down by more than 5-thousandths, try the neck sizing in successive steps of 0.005" or less. That tends to stop the overshooting you are getting and give you results that match the bushing diameter.

 

[mikecr]

As mentioned it gets harder to predict larger steps in sizing. As well the hardness/softness of the neck affects the amount of springback from any sizing action.
Have you recently annealed necks? This could leave them smaller than expected after sizing.