I always wondered about using s mandrel with a Dillon set up. As soon as I get more room I'm going to be looking into one of thr Dillon set ups
TLDR: Despite what some people write, you can load good precision ammo on a progressive press. This describes my "hybrid" process. If you don't care, don't waste your time reading this!
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My process for precision loading on an RL550 uses two tool heads. The first head has a bushing size die in station 1 (primer is seated at top of up stroke), the mandrel in station 2, and seating die in station 3. Lubed cases proceed around the press as usual but stations 3 and (empty) station 4 don't do anything.
After resize/prime/mandrel, I clean the lube off the cases, put them mouth-up in loading trays, and then use a q-tip to lightly apply Imperial graphite lube to the inside of the neck. This step may or may not be of much benefit but it takes maybe two minutes to do 100 cases. Then all cases are turned upside down in the tray.
I then insert the second tool head, which contains a full set of Dillon .223 dies - resize (with expander ball in place) and prime in station 1, powder measure in #2, seat die at #3, and taper crimp at #4. I use this head "as designed" for blaster ammo.
For precision, I'm only using the powder measure*, which I set to drop a tenth or two light into an empty case. This powder is dumped into a tray which is placed on an FX-120i scale and the charge is trickled to desired weight. Then a primed case is turned mouth-up and the weighed charge funneled in, and a bullet is set in the case mouth**.
After all cases are charged as described, I empty the powder measure, and put the first tool head back into the press. Bullets are seated. Done.
I don't pretend that my approach is fast. That's not my point here. Early on in my precision rifle experience, I was concerned that my 25-year-old progressive press wasn't suitable for precision handloading. But, with rubber o-rings allowing dies to "float" just a bit and several thousand rounds loaded over the last three years, I know I can keep runout under .004" and it's usually better than that (I do not turn case necks; been there, done that, pita to no discernible benefit with good brass, no more).
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* Of course, for bulk-loading any cartridge, the powder measure must be adjusted for the caliber being loaded. I cheat a little here. For .223, the measure is set to drop a full charge with a full handle stroke as designed. But for 6.5CM, I just swap in a different charge bar which drops the heavier charge and stop the handle short of full stroke when the longer case hits the limit of the charge bar's travel.
** I used this approach because, for me personally, it has eliminated the occasional uncharged cartridge I let slip by early on. Hand loading precision rifle cartridges is such a repetitive, brain-numbing task that, if I had 100 empty cases mouth-up in the tray, charged them all, and placed bullets when moving case to the seating die, I would occasionally leave a case without powder. Even when I tried to make myself check cases after charging.