Since I have this super sensitive 21st Century run out gauge, I have learned a lot about reloading. Now, I also have a Widden precision 6.5x47 FL bushing die also.
My observations are that if the neck OD/ID has runout, the loaded bullet will have as much - or even more runout at the ogive.
1. Fired brass has nearly no runout on the neck OD, if your rifles chamber and throat were reamed round and concentric. Most of my barrels are excellent in this regard.
2. Most of the typical sizing die operations in reloading, destroy neck run out on fired brass because the equipment is crappy and the operator doesn't know he is hurting the neck runout.
3. Neck sizing bushings are not intended to correct runout. They are intended to float "loosely" radially and vertically in the die and will not make runout worse than was is previously. They just size the OD of the brass neck - if it is ductile and does not have memory.
4. We know we can jam the bushing down into the bottom of the die, and straighten up necks, but it's a real trial and error deal.
5. When you push back the shoulder without a neck bushing in place, the dies shoulder taper may not push back the shoulder evenly, causing the neck cylinder to tilt. This makes for neck run out. A bushing is needed just to keep the neck cylinder from tilting excessively.
6. Neck ID sizing mandrels - even special ones - and size buttons generally wreck the neck run out.
7. Nearly every tool that touches the neck needs to float. I have a #17 o-ring under the shell holder, and one under the FL sizing die. This helps compensate for the crappy press machine dimensions. The shell holder and the 7/8 die bushing are definitely not on the same center.
8. If you size the fired neck down, then back up again with a mandrel or button to fit the neck turning lathe mandrel perfectly, you will have perfect wall thickness, but potentially a bunch of neck run out. Sizing the neck, just for turning is dangerous in this respect.
Bottom line is the necks from fired brass should be treated as gold. All devices that touch the neck must not be rigid or influence that cylinder of the neck in any way.
To keep the bump or FL sizing die from tilting the neck, you need to set the die up carefully (with o-rings) and use the run out gauge to verify the die is set up okay with no damage to the neck, before running a bunch of brass. Do this, and you can run 50 brass easily with neck runout at .002" or less. It's damn near impossible to do this any other way with the equipment I have.
You all may know all this already, and either agree or disagree, but this has been my findings.
Glenn
Sent from my iPhone
