Do single stages really produce more accuracy than progressives?

The only way I got my Dillon 650s to crank out suitable 'Match' grade brass was by using two sizing dies,
One that only punches the primer, no sizing ball, and has the neck hones out so it doesnt over compress the neck, and sizes to more or less what I'm looking for,
The second is high precision, sizes the neck to exactly what I'm looking for.

Then its off the trimming for length with a datum point trimmer...
*IF* the case is going to be off on length, I'd rather it be in the neck rather than the headspace...

My Dillon required some TLC, not all tool heads are created equal, and shimming them turned out to be a requirement,
You have to keep a CLOSE eye on the shell plate to ram bolt or it introduce slop,
And I put a rod down from the tool head that contacts the shell plate opposite of the sizing dies to stop shell plate deflection.

I've also installed a 'Button' under the first sizing die in the ram 'Cup',
Hole for primer to drop through,
Helps stop deflection by supporting the case/shell plate while on the 'Up' stroke.

Actually, I think the thing that helped most was the rod opposite sizing dies, down from tool head. Incredably easy to do and keeps that shell plate from toggling...
Wish I'd thought of that before I ruined the first ram 'Cup' trying to figure out the button!
 
Like many reloading procedures, actually quantifying a small potential difference is difficult if not impossible.
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There's this old cliche about art and science, and it fits. Science and mechanical expertise are not the absolute final answer in this field. When you are dealing with variables that control ultimate accuracy, I suppose that the press is probably pretty far down the list of things that will cost significant accuracy. I suspect that unless you can reliably turn out 1/2 moa groups or even smaller, it won't matter. the difference between a $400 single stage and a $1,000 turret or progressive that is designed for match rifle loading is going to be kind of moot unless you have cleared all of the other hurdles first.
 
I just ordered a ton of match grade 308 MatchKing 180 grain bullets
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If that's the case, I'd stick with the progressive. 78,000 rounds on a single stage would take over a lifetime to roll.

Just sayin'.....:D
 
You have to keep a CLOSE eye on the shell plate to ram bolt or it introduce slop,
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That is where the 550 is superior to all the other Dillon progressives, the shell plate is only there to pull the case from the dies. The bottom of the case does not ride in/on the shell plate.

A ton of brass isn't as much as you think, each one of these has more than a ton in them.

IMG_20140221_191342_zps4ec6891d.jpg
 
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