Originally Posted by Bart B
I think that your case mouths are way too small if they're .008" under bulet diameter.
Unless you die's neck has bushings sized .002" under loaded round neck diameter or is that size already, they're not being expanded enough. That's what the expander ball does. Standard full length sizing dies make sized necks way too small without the expander ball being pulled back up through them.
I was thinking the exact same thing but thought I would let someone smart answer this. The general rule I see out there is .002 neck tension. If you look at Lee, RCBS etc they all say .001-.003. I was encourage to run .002 for enough tension to hold the bullet securely for a repeater. I assume I am doing things correctly at this point. Perhaps you could give it a shot.
Here is what I do:
1. measure the loaded neck...example. .294
2. .294-.002 = .292
3. Insert bushing. Neck size. example .292 is the sized neck.
4. check chamber neck space, measure fired case. Example .296*
*did not know how good or bad this is for me. just knew it was enough to allow the neck to expand some. I assume it is actually a bit larger since the case grows and retracts a bit.
With a neck bushing I don't use the expander ball. I use the small end to punch the primers only. With a FL die I have to use the ball, the neck is way tight, such as yours.