Re: Neck turning questions?
All good questions, but no standard answer for most.
neck tension is like women. most guns like different ones. generally .001-.0015 is very minimal and used to "soft seat" into the lands for br guns. You run the risk if you open the bolt with round in the chamber of leaving the bullet in the lands and dumping powder inside the action. Most hunting rigs you will want .003-.006 max if you neck turn.
Some bullets like heavier neck tension. For example the 187 gr BIB flat base match bullets tend to like .003-.004 minimum while most match guns shooting VLDs like .002-.003 max
as for standard wall thickness, depends on the mftr, caliber and lot. However, most factory are around .014 minimum to around .018 max with the norm if there is one at around .016
clearance- optimum for what? Most BR guns are set to have as little as .010 to .015 clearance total. Hunting guns I want .002.003 minimum, if I have a min SAAMI chamber and neck.
Neck turning will not solve runout normally unless your brass is really screwed up. If you neck turn brass in factory chamber you are making it much looser in the neck. For example most 30 cal factory chamber necks will be around .348-.352 or so with the most at the upper end. Most factory loaded rounds will probably be about around .338-.342 or so. So if you neck turn a case from .015 to .013 in a .350 chamber with .308 bullet you have extra room of .016 or .008 on each side.
Most of the short range br guns go to .262-.263 necks with .243 bullet so they are running .0085 neck thickness. That is really thin and easily damaged.
I am running .338 neck chamber in 300 WMS and turning necks to .0135 or so.
No sweet spots for any thing. Like I said the short range BR guys have run .262-.263 necks as the standard and all of a sudden guys are not using .267 and .268 chambers and doing real well. Less neck turning and less damage to cases.
Anytime you take over .003 off a neck you are talking multiple passes with the turner which creates extra heat and runs the risk of damaging the neck. That is why I set my neck dimensions to be just small enough to clean up the neck and work. ie .336 for 30 cal and .269 for 6 BR for example