how much variation is normal in seating pistol bullets?


November 1, 2006, 10:58 PM
I've been reloading for over a year, on my Dillon 550B and recently bought a Redding Competition Seating die to reduce variation in my .45acp loads. The rest of my setup is a EGW U-die and a Redding taper crimp die. I expected to see next to no variation, but that is not the case. I'm seeing as much as .003 variation. After much tinkering I got the variation down to +/- .001 consistently with the occasional -.002. Am I being too anal, or is this all I can expect of this specific set up?:banghead:

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November 1, 2006, 11:05 PM
I'm new to reloading but I see some variation as well. .001" is TINY! I personally wouldn't worry about +/- .0015"

November 1, 2006, 11:22 PM
a few thousands either way is all i want (+-.002)

i'm not a bench rest shooter though, and 600 yards is as far as i shoot. differences will be more obvious the farther out you go.

November 2, 2006, 10:06 AM
As I understand it, the variation comes from the bullet.

Seating dies contact the bullet somewhere other than the tip.

Unless using a specialty tool, we usually measure from the base to the tip.

So any variation in the shape of the bullet can result in variations in OAL, even though the seating die may be seating to an exact length from the base to where the seating stem contacts the bullet.

November 2, 2006, 11:54 AM

Interesting point. I assumed that the seater contacted the top of the bullet.

Thanks, JSM

November 2, 2006, 02:20 PM
Yes, seater dies usually contact down around the ogive of the bullet.

Admittedly, I actually don't know how much variance I get out of my loaded rounds in OAL. My .223s fit my AR-15 magazines, my .44s fit and feed out of my Marlin, I'm happy.

I actually think there is enough to variation in some rifle bullets that a comparator is the best way to measure you OAL, especially for rounds fed singly.

Of course, I also don't blink at .1gr powder variations either. If you're in the sweet spot, a small difference here or there won't be the end of the world. Unless you're shooting benchrest, but I've never shot 600 yards with anything but my mat, glove, jacket and sling.

November 2, 2006, 05:53 PM
I thought about this a minute, and want to nitpick myself.

Sometimes the seating stem does contact the bullet's tip:

In the first instance, when loading flat-point bullets using a flat-point seating stem.

In the second instance, when using the wrong seating stem for the bullet: For example, a seating stem contoured for round-nose, and a bullet that's "pointier" than the cavity ground into the seating stem.

November 2, 2006, 06:54 PM

If you've selected the correct seating stem for the bullet you're using and adjusted the die in, then you've done about all you can do. If you still feel uncomfortable, call Redding and talk to their technical folks about what realistic expectations are for reloading pistol rounds on a progressive.

Remember, the level accuracy needed for most pistol is way lower than what is needed for rifle. Most folks cannot shoot accurately enough to outshoot their "inaccurately" loaded pistol rounds, even the bullseye shooters until they're reaching higher competition levels.



November 2, 2006, 08:12 PM
I typically see +/- 0.002" in OAL, but I attibute that to variance in the bullet shape and differences in casings. My practice loads are done with mixed brass so there is some variance. I wouldn't sweat it.

November 2, 2006, 08:58 PM
I would not complain about plus/minus 0.003 in seating depth variation.

November 2, 2006, 10:09 PM

After reading your post I realized I never went to the source - Redding. I found a page in their tech section that describes variances and recomended steps to prevent them. If you're interested you can go to:

Thanks for the help.

November 2, 2006, 10:42 PM

You're welcome.

Back a few years when I was a Manufacturing Tech., it seemed like I was always on the phone with one equipment manufacturer or another figuring out if the tolerances we were getting was the tolerances they designed the machine for or if we had a problem.

I wish our engineer at the time had done a better job of matching "expected tolerances" with the machines' capabilities. Would have made my job a lot easier.

What I learned though is most gadjets that are mechanical have some expected tolerances in what they produce. Reading gives you a good idea of what something can do. Of course, from a practical side, it never hurts to call and actually talk to a human that has experience working with the doodad you're trying to get going. He can pretty quickly tell you if you're realistic in your expectations or if you're "sweating the small stuff."



Chuck R.
November 3, 2006, 12:01 AM
With my Dillon 550 I see about .003 variance in loaded .45ACP LSWC rounds.

I tried tracking down the source and found that it mostly occurred after taper crimping as a separate step. The seating process was pretty uniform, but I think the bullets are swaged some when applying the .469 taper crimp.


Rabid Rabbit
November 3, 2006, 09:01 AM
I get +-.001 but I do know people that are fine with +-.005. I'm not sure what they are doing wrong but they don't seem to care. They also tend to make light loads so it may not be such a big deal for them.

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