straightness

[bota]

I recently purchased a sinclair run out gauge, and found out that all of the rounds i am loading are very crooked. I thought that the problem may have been my seating die, so i got a forester bench rest seating die. This didn't help. I am using a brand new rockchucker press, and its operation seems to be good.

When i measure my fired brass, there is usually <.001 run out on the neck. After running the brass trough my sizing die, run out increases to ~.002 or .003. Then run out increases to .004 to .008 on the seated bullet when measured close to the neck.

I am not sure how to fix this, but i am thinking that a better sizing die would help? What would you guys do?

[britz]

Much of runout is caused by the expander ball in the resizing process. You may want to use some extremely fine grit sand paper or wire mesh and polish the ball to reduce the friction.

[Winchester 69]

Expander ball?

[bota]

thanks for the replies. I will try the suggestions in the expander ball thread. Is the small amount of r.o. introduced in the sizing stage leading to the massive r.o. after the bullet is seated?

[trueblue]

bota,
just resize without the expander ball, but make sure you check how much neck tension that gives you.

[Moman]

Bota, what kind of sizing die are you using?

[bota]

RCBS sizing die. How do you check neck tension?