Sandman,
There's many of time I wished I lived in Eagle River too, as most of my work has always been there in Anchorage. Stopped by there and had a cold one with my buddie Charlie on my way home last night. I'm pretty used to the 40 mile commute by now though, and it's warmer in the Knik River valley 10 miles east of Palmer. It's a cold windy SOB right there in the Palmer Wasilla area.
I'm guessing you have a tighter neck chamber than factory, but I need the diameter from fired (unsized) cases to really determine how much a specific size bushing will "actually" bring down the neck diameter, which in turn determines the amount of press fit.
The amount of neck sizing is really determined by the differential in diameters of the fired case being sized and the bushing size. The angle that the case mouth enters the bushing determines how closely it fits and follows up into the bushing the rest of the way, i.e. super loose, loose, perfect, tight, or super tight.
Example - If the case neck is .344 diameter after firing and you try and size it down with a .335 bushing, the neck enters the bushing at a sharper angle than it would say, a .339 bushing, and will literally overshoot the bushing ID and end up smaller than the .335 diameter which is expected. In this case, you probably would see the neck be sized down to somewhere about .333, not .335.
On the other hand, if you ran that .344 neck up into a .343 bushing it will follow it so closely that it's super tight on the bushing, then the brass springs back and you end up with the same .344 you started with, again not what you expected.
There's two things you need to account for when using bushings on brass, spring back and the amount you're trying to size it back down by (the angle it enters the bushing).
If the entry angle is great (loose chamber neck), it will overshoot the bushing ID and end up smaller, plain and simple.
If the entry angle is very small (tight neck chamber, .002 total clearance), spring back of the brass causes the neck to end up larger than the bushing ID when withdrawn.
Here's my latest example that might help to illistrate this better.
My chamber's neck is .335 on my 30-338 Lapua Imp, necks on the fired brass come out at .335 diameter.
Firings 1-4
A .334 bushing yields no downsizing.
A .333 bushing yields about .3345 necks.
A .332 bushing yields about .3333 necks
A .331 bushing yields about .3320 necks
A .330 bushing yields about .3308 necks
Firings 5-6 (necks harder now)
A .331 bushing yields about .3329 necks
A .330 bushing yields about .3319 necks
I turn the necks down to .1235, so I end up with nearly .001 tension on the new brass using the .331 bushing. Loaded rounds are about .333, for about .002 total clearance. After firing about 4 times, not including the initial case forming, the necks harden up enough that neck tension is practically nothing on the 5th loading, so I drop to the .330 bushing, even though annealing is truely in order. Annealing should really be done after a firing or two at most just to maintain a consistant neck tension with the .331 bushing.
I hope that's not too confusing, but your neck diameter of the fired cases is what will really tell you what bushing to start off with.
If you're getting variations in neck diameter from .336 - .337, I suggest they could be cleaned up with turning to eliminate that. Without running an expander through brass with uneven neck thickness, this will immediately translate to uneven neck tension, and possibly irratic behavior in groups, i.e. fliers.
It sounds like you already have a nice baseline to evaluate further changes. I found this one rifle did not like .002 neck tension at all, groups increased by more than 50% immediately, right back to normal with .001 tension.
I'd shoot for .002 tension and see if bullets seat deeper on recoil and only go with more if they require it, less if not, just to test it anyway, .001 may still be enough. It takes about 75-85 lbs of seating force with .001 press fit on the 30 cal with fairly new brass, but drops to 20 lbs force or less as necks harden up. Experiment a bit and you'll see what works, and what it likes and it does not.
Just C,
You can remove the bushing on the FL bushing die to size the case and bump the shoulder, or buy a body die Redding sells.
I set mine up with a Stoney Point headspace gauge on the caliper, just measures base to shoulder is all. I measure the length to the midpoint on the shoulder on a well formed case (from a good hot load), which happens to be 2.260 on the 30-338LI. Then I incrementally move the die down until the shoulder sizes back .001 - .002 where closing the bolt on it when chambered still has slight resistance on it indicating it's still tight on the shoulder at some point on it, which keeps the neck centered with the bore best it can. A "very" small adjustment on the die each time is all that's needed, go too much and you'll have to start over with another case to get it set up. Don't forget to lube and clean the case each time though.
Once you play with it a while sizing a neck without a supported case body, or sizing a case body without sizing a supported neck, you'll see how runout in the neck goes to hell in short order. It may take a firing/sizing cycle or two to get bad, but that's why I FL size and bagged the neck sizing all together. You still have to keep the shoulder bumped back anyway to keep the bolt closing acceptably, usually every other firing in my experience. Runout was the only reason I stopped though, it's just uncontrolable without FL sizing.
If you're only wanting to size the diameter of the body at both ends and not bump the shoulder, which is what you may be wanting to know, I'm not sure but, you want to measure the length to the shoulder if you keep the die up a tad... it will lengthen the shoulder as it squeezes the body down in my experience. In most cases, the case becomes way too tight to chamber after it is sized this way... check it "before" and after in the chamber as well as measuring the length.
If you don't have the Stoney Point tool for checking the relative base to shoulder length, just use an empty pistol case that fits to the midpoint on the shoulder and measure from casehead to casehead to monitor shoulder bump compared to the length of the baseline formed case. A 44 Mag case works well slipped over the Ultra mag shoulder, a 475 Linebaugh/480 Ruger case on the big Lapua case but, the only one that works well for the 308 is a 41 Mag or 375 case.
Sorry for the long post! Hope that helps though.
