Re: Neck turning vs Bullet seating pressure
Are you sure there is .007" difference in diameter along the neck? That seems quite a bit excessive, does you're mic read to the ten thou, and might it be varying from .3400" to .3407" if it does, 7 ten thou? This would make more sense, not to say yours aren't 7 thou smaller at the mouth, cause they just might be. Just a thought. For these type measurements, my dial caliper works just fine. The one measurement that is sometimes is impossible to get with a caliper, even for just comparison purposes is, neck thickness. Sometimes the brass will do almost like your measurements suggest, almost roll, or taper inward near the mouth, so trying to measure somethings thickness that isn't parelell on the inside and out just measures larger than it really is. You can measure it right at the case mouth with fairly descent results, just that the deeper you try to measure thickness, the larger number you get when that's not really the case. A ball mic is the only way to go for the deeper measurements, or seat a bullet and take an outside measurement, and a caliper works fine here for relative comparison purposes, and I'm sure a couple three ten thou resolution isn't a stretch either.
At any rate, before and after seating outside diameter measurements up and down the neck will tell you what amount of press fit you're getting along the necks length.
You're right, I don't use an expander ball. I should have said that in the beginning.
I had to use it on the cases that sized down too far like the ones you did, oh, and I swear they were altering the headspace it had so much resistance, like to jerk the necks right off of them!!
So I didn't have to use the expander after that bout, I turned the necks down just enough that I'd get .003" press fit without the expander using that bushing, that's when I found I got the same press fit when running them through the FL die too, with no expander. Turned out that was just a bonus I hadn't expected.
It followed the finished bushing size to a tee.
Just got lucky I guess having a chamber in between the huge rem chamber and a tight neck custom.
I think you hit the nail square on the head there. That's about where I'd expect it to work about right also. The reamers that are held to a little tighter specs should all work about like that I'd figure. My dad has a couple chambers just like that, .003" to .005" total clearance with loaded ammo. I'll have to ask him what he's getting as compared to his bushing size.
More than anything, I just don't like using an expander, although it's said RO can be made worse using one, that's not the real reason I don't. I just haven't found any difference with or wothout, but I don't lock mine down either, I just let it float. That may be making a difference. They're never in the center when locked down on any of my dies, so I figure it would be better to leave it loose to let it center as a drew the neck back over it.
The main reason I don't use it is, if I have to, I'm obviously sizing it down farther than I need to, thus working the neck more than's needed. That, and I've never liked getting lube inside the neck, or cleaning the stuff back out with a patch and brush. The carbide balls work a little better, but I lubed cases using them too, just went a lot smoother still. If I tumbled or vibrated brass to clean it it probably wouldn't be a big deal keeping the necks consistant. A little more lube left on this neck than that one didn't instill confidence in consistant neck tension. I ain't lookin to will a beauty contest with my brass, so they get the lube wiped off of them and that's clean enough for me. Vibrating them to me is a complete waste of time and effort. Powder build up on the inside of the case, with the powders I use, are totally insignificant.