After reloading on a Dillon 550 for about 10 years, I got really good about knocking out lots of pistol rounds quickly. Then I got into rifles and have been trying to mass load .223 and group tighter than MOA. Using ladder loads CCI41's, H335 & 69 gr Noslers I found that 23gr at OAL produced the best results.
Then I went a step further.... I hand prime & I found that if I used the Dillon starting with position #2 (powder drop) instead on using position #1 to prime that the OAL varied up to .015 if I populated the final 3 stages at the same time. This type of tolerances on completed rounds produced 3" groups at 100 yards (totally sucked) which I didn't mind with my AR pistol but out of a rifle are totally unacceptable! I would load the primed case into Position #2 and drop the powder (H335 is granular so it feeds consistent), then I would rotate the powder filled case to position #3 and place only the bullet (leaving position #2 & 4 empty). With the bullet seating the only operation being performed on the press AND using a very soft stroke to seat it I have been able to get the OAL to -.0000 +.0005 - Yes 1/2 of a thousandth of an inch!!
Then when I rotated the newly seated bullet to the #4 crimp stage AND I would repopulate the powder drop and repeating the cycle. By doing the seating stage by itself I was able to eliminate the .015 variance! With these rounds at 300 yards I was able to group at right about 4".
Now for the last couple days I used the calipers and separated all my brass by length (I used a duct tape on my thumb). I'm thinking that if the cases are all the exact same length (I mean EXACT), with a consistent powder feed and the same OAL I should have the same pressure which should increase the accuracy?
So what do ya think? Am I too OCD???

I've thought about small rifle primers other than the CCI 41's (because they are a bunch cheaper) but I picked up a bunch of these a few years back for about $30 per K. They ALWAYS go bang!

Is this to be shot out of a semi auto AR platform?
I would think being slammed out of the mag, up a feed ramp and then into battery would negate some of your effort.
Or are you using a Bobsled to load single rounds?

www.gunsamerica.com/blog/reloading-scie ... brass/amp/

Interesting read





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This is out of an AR with a 24" bull barrel. I was in Montana and an old guy asked me
What are you shooting? When I said an AR15 with a 24" Bull Barrel he said
"Son, that's a keeper because I've seen guys shootin' those things who couldn't hit their ass with a handful of rice!!!

I load for a Cooper 21 in .223 on my Dillon 650. I use the threaded toolhead fasteners and adjust things with all the stations full. Any variance I get can't be seen in the groups and I've loaded and shot thousands that way.

This is out of an AR15 with a 4x12 optic out of my bull barrel platform

That's cool and all, but at some point you're picking fly shit out of the pepper.

I honestly don't know where we cross the line from the ammo being the limiting factor to the rifle.

Not being a toilet scientist like Madpick all I can do is rule out as many variables ass possible...

Well, this toilet scientist feels like his progressive press does just fine.

But can you load within .0005? No TP required!

I don’t know, I haven’t measured it. Are you measuring true OAL or to the ogive?

just add a tint of blue

Well this conversation quickly went into the toilet.

Bam...

From Re-loading to Boner measuring...just like that.

Next they're gonna say you gotta chamber a slightly loose bullet set long to see where the lands hit and get that compressed/set by the bolt as a true OAL and subtract a couple thousandths....5 or so so the 'bullet' doesn't have far to jump.

At least thats what they did in the 'Old Days" to find True OAL for that chamber.

I'm really itching to get back out to Montana. I load all my prairie dog ammo on a turret press and crimp pretty hard to avoid set back on my AR when it chambers. That being said my AR is a murder machine out there. I've got many long range kills and outstanding consistency at mid range.
I'd drop 30-40 charges on the progressive and weigh the powder. If it's consistent weight then seat and crimp 30-40 and measure with calipers. If it's consistent length then shoot them over the chrono. If it's consistent speed then who cares what kind of press you load on.
Consistency.
My AR is a mossberg mmr hunter 20". It ain't the rifle doing the work. It's the ammo, and a little bit of luck + practice