Originally Posted by Mikecr
Two reasons you can't get below 3thou in TIR Bart:
-You haven't culled out cases with thickness variance
Also, there is a difference between separate or combined body die/partial neck sizing, and actual FL sizing. They're not the same.
'Full length bushing dies' ARE NOT FL dies. They do not full length size.
Bullet Bumper's post pretty well described a few potential approaches to reducing runout.
Missed, maybe I missed, is that there are three main causes of runout:
-Poor cartridge design
A 30-06 brings all three to front & center.
It's length to width to cal is all wrong. It has high body angle and low shoulder angles.
This causes an immediate need for greater sizing than better designed cartridges ever need.
Any thickness variance bows a 30-06 more than better designed cartridges.
It is ballistically inefficient and much of the unburned powder merely adds to bullet mass, increasing recoil and muzzle pressures.
When you find no gain in straighter, better chambering fit 30-06 cases, it's because you've already reached the cartridge's potential(it's not a bench rest cartridge).
I agree . Thickness variation is a big issue and that's why I use skim neck turning and the long neck is perfect for partial length neck sizing .
The 30-06 will never be a modern BR cartridge but with the right approach it can shoot very well .
As Bart B points out minimum sizing is also a good idea to preserve case fit and reduce the tendency to distort the case neck centre with older dies.
This is why I use Lee collet die , with shortening washer and Redding body die.
The less you have to size each time the better.
However with hunting rounds fed through magazines we also have to have adequate neck tensions .
I would not say that the 30-06 is ballisticly inefficient it does a great job with the powder it consumes compared to bigger volume magnums . So in that direction it is effecient . Not really fair to either , to compare a 30-06 and a 6 mm PPC .