Has anyone with the skill and concentricity measuring device ever actually compared runout on cartridges made with standard sizer expanded necks and cartridges made with expander die in a separate step? Any actual accuracy improvement upon shooting said cartridges? Noticeable in AR platform as opposed to bolt gun?
Yes. I’ve done all of this.
Yes, runout is improved a lot. I float my expander die mandrel (leave it slightly wiggle loose in the die) and still get a little runout. But it’s much better than an all in one die.
Accuracy would really depend on the bullet and barrel. But for me, there’s no big difference. I once sorted off all the worst runout rounds in a box of BH 175gr SMK ammo. Then shot them against the straight rounds in the same box. No discernable difference.
In my experience, tangent ogive bullets don’t much care about a little runout.
The main reason I stick to the expander die as a separate step is that the brass doesn’t get brutalized and there’s no additional case stretching that I have to trim away.
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Yeah, my SB die expander stem is also loose. Shell holder retaining clip removed from ram. Inside of necks lubed for sizing (and before seating). Ram worked gently and in stages as I watch for base and shell holder alignment.
The Giraud trimmer requires technique for reasonable results. I still frequently get uneven inside deburring. Fall asleep at night wondering if it’s wall thickness or crooked necks. (My concentricity measuring device is a flat piece of aluminum that I roll cases on…)
My process is tedious enough without adding another step! Still, I do tend to check boxes so I can blame poor shooting on myself instead of my equipment…
I don’t even lube the inside of my necks. The expander die doesn’t give me enough resistance on the press to make me think it’s deforming or distorting any of the brass.
And, yeah. I twist my brass in the Giraud to try to get even chamfering in the mouth.
So, I measured headspace and oal of 3 range pickup cases (wcc84) ea of inside neck lubed and non neck lubed. Ran them into a SB 223 sizer. Removed case with expander stem still in case and made the 2 measurements. Reinserted cases w/o sizing body just to pull button through neck. Re measured. Oal measuring with stem still in case was a pain, but results were consistent.
Amongst all cases, fired hs was within .003. Sized hs was within .002, setting shoulders back 2 1/2 to 7 1/2 thou.
Headspace change did not seem to correlate with amount of oal growth. Sizing the body resulted in approx 5-8 thou oal growth (even as hs shortened). Pulling the button through the neck added 0-1 thou with no real diff between lubed and non lubed necks. It appeared that sizing (and associated brass flow?) caused much greater oal increase than pulling the button through the neck.
As said earlier, I have nothing to measure runout, so no comment on that. Even then, I have been called both Elmer and Fudd…
Fwiw.
That’s pretty interesting. I can remember pulling the button through many years ago (before I knew it was even in there) and feeling the somewhat heavy drag from the upstroke of the press arm.
I would have thought that would have been more like 3-4 thousands. In either case, the necks were surely straighter from my equipment.
I don’t have the equipment and will trust what you’ve measured. I have wondered about alignment issues and pushing shoulders back should M dies and the like be used unjudiciously, but I doubt it happens. Less runout as measured is what it is! I just wish you had been able to unequivocally state that it makes a difference on target and is worth doing! Your objectivity is respected even as I try not to add the separate step.
I just wish the Giraud solution was as easy as a simple twist. For me it’s hesitate at a gentle first contact, slow and gentle feed. Repeat. Pressure is the enemy. Inspect. Then touch up all cases with my Holland or whoever made it inside deburrer… Aaaaggghh… Just to shoot bottles and cans at my feet!
There’s a lot to drive you insane with handloading rifle ammo. I’ve quit worrying about much of it.
I try to do what I think is the best process within reason.
As far as the Giraud… I just cut my brass a little long to minimize the uneven chamfer and increase the remaining neck surface that contacts the bullet.
If I can keep MOA ammo and my sanity, that’s the balance.
If we are talking AR grade ammo made with 55 FMJ bullets, then I don’t worry too much about it.
For precision ammo, I use a mandrel die. The Giraud inconsistency hasn’t affected my groups enough to notice. Annealing has helped more than I thought it would.
Like markm said, the bullet and barrel make a bigger difference than anything else
I only have one sizing die. So even if I’m loading the occasional blaster FMJ, I still use the neck expander just for simplicity… even though it’s an extra step.
Any specific product recommends or avoids?
Easy button would be Lyman, I guess.
But now I see others where you can get varying mandrels to experiment with neck tension. Anybody done this?
One is even oversize so you can “straighten” the neck before full length sizing to allegedly help with runout…
Best mandrel material? Tit, carbide, stainless? (Don’t think I’ll fool with nitride?)
I’ve only run one. The RCBS .224 (I think) neck expander die. It’s a stainless mandrel. I’ve sized thousands and thousands of necks and thought it might wear down. But it seems to be the same as ever.
Sounds good to me (I am an RCBS fanboy…)