BDS, A few months ago I bought a 1000 cases of LC .762 from Wideners. I knew it was probably MG brass, but I wanted to see what could be made of it, not for benchrest ammo, but for very accurate AR 10 ammo. (Remington R25 to be exact)
I bought an RCBS Case Master Concentricity Gage. I have and use a .308 small-base sizer, and a Gold Medal Seating die. I also use a Hornady OAL gage for keeping bullets off the lands a few thousandths, and an RCBS mic to set the sizer shoulder bumping. (Note: for the R25 the magazine length was way shorter than the lands, so that determined maximum OAL).
So with that I wanted to test the water. I blinged a 100 cases in a wet/stainless pin media tumbler, that left me with very shiny new looking brass.
The next step surprised me. Sizing! Yup it must have been MG brass. It was sizable but not easy. The usual process, using a little Imperial wax would not size this stuff. I think my brass, blinged as above created, even more friction than the MG (machine gunned) alone did. Long story short, RCBS lube pad was necessary, with a little brushed inside the necks. (gee, I've used Imperial for years)
Next came the brass neck runout test: Using the RCBS gage it ran from .002" to .008" using the sizer's included expander button.
So I removed the expander button and retested: The gage measured .001"-.002"
I won't go into the details here, but I reinstalled the button, resized a dozen cases 3 times each rotating each case 120 degrees, and remeasured. They all came out .001"!
Interesting, yes? I know resizing work hardens the brass, but I wanted to know.
So then, I was left pondering about the other options:
1. Bushing dies: Yes, they do away with the buttons that tend to yank shoulders out of concentricity, but they aren't perfect either. For one thing they can't size the whole shoulder, for another they are loose in the die so perfect runout is pretty elusive still.
2. Old time benchresters used to remove their expander buttons and hone the insides of a regular sizer's neck, to open it up enough to seat their bullets. It worked VERY well. Runout was mostly eliminated.
Only problem was that neck thickness had to be the same for all brass......or make another honed sized for each kind of brass you use.
Anyway, it seems that
Forster provides a cheap $10 service if you buy their sizer's! They will hone the necks to any diameter......
usually bullet diameter minus .002" plus 2x neck thickness. I aim to try that....or maybe hone my own small-base die. So using .308 bullets, the target diameter would be .306" plus neck thickness. Anyway, jury is still out....will let you know how it turns out.
3. The third option is using a Lee collet die.......who can tell us the pluses or minuses of that number?? I have never seen one......I do know that it only neck sizes, but
perhaps it could be used after the small base die minus the expander button?
My experiment with this LC brass is ongoing....I have not shot any of these rounds yet, and only seated a few to test the effect of the Gold Medal Seater on near perfectly straight necks (.001") The result typically was to add a thousandth....finished rounds have been .002". Can't wait to shoot a few in my Remington R25!
Perhaps the above may jump start this thread with experiences of your own.
