SAC modular sizing die setup

JRBullock1987 · Dec 22, 2024

What's a good neck/shoulder bushing and expander mandrel size combo for the SAC modular sizing die for 6.5cm? Im thinking 286 for the bushing and 262 for the mandrel? I got the 283 (which is technically for 25cm) and 261 for the expander mandrel. I watched and followed Gregs (from primal rights) video on how to determine what bushing and expander mandrel sizes to get and now when sizing my brass the shoulder will bump the 2 thou i want but is only sizing the top 2/3rds of the neck so now I've got to find another combo that works correctly. I set up the die using their YouTube instructional video and i also asked sac if this combo was ok for 6.5cm before getting them and they said yes but obviously it's not working out so well. so now I need some help to find a combo that sizes my cases correctly and effectively. My brass has 13.5 neck wall thickness, which is why I chose 283 to get me about 5 thou squeeze to then open back up with 261 (a little over 3 thou after spring back)
Thanks

spife7980 · Dec 22, 2024

I’m pretty sure the unsized base of the neck is by design. It’s not an issue.

I always say to get a bushing .003-.004 below a loaded round diameter and a mandrel that’s .002 under the bullet diameter. It’s a nice baseline, experiment from there.

.0135+.0135+.264=.291 loaded round diameter if your measurements are to be believed. A .283” bushing defeats the purpose of a bushing die (minimizing brass movement) if you are going to overwork your brass that much anyways.

JRBullock1987 · Dec 22, 2024

spife7980 said:
I’m pretty sure the unsized base of the neck is by design. It’s not an issue.

I always say to get a bushing .003-.004 below a loaded round diameter and a mandrel that’s .002 under the bullet diameter. It’s a nice baseline, experiment from there.

.0135+.0135+.264=.291 loaded round diameter if your measurements are to be believed. A .283” bushing defeats the purpose of a bushing die (minimizing brass movement) if you are going to overwork your brass that much anyways.

That's what I always thought too. I watcheded greg from primal rights video and followed his calculations on how to come up with the right bushing. Normally I don't use bushing. Just fl sizing die and then a mandrel but I liked the precision you can get with the sac die with less case runout as well as having the case supported while the mandrel pulls through otherwise I'd just use a non bushing die.
Heres the link if you feel like looking at it. Idk what to think lol

Cafard · Dec 24, 2024

I have used the same bushing and mandrel for the exact same cartridge and brass neck thickness. .261 mandrel + .027 brass = .288 - .005 = .283 bushing. I have no issue beside runout being between .001 and .002. I have ordered a .285 bushing to see if it help a bit. TBC

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