COL Variance Help on XL750

[drewfoo]

First-time reloader using a Dillon XL750 set up for 9mm. I'm loading Montana Gold JHP 124GR, Ramshot Silhouette, CCI Small Pistol Primer, and Mixed 9mm Brass.

I got all the dies set up working well but have seen a lot of variance in my COL and seating die. I've tried a couple of things to bring the variance down - i.e. calibrated with a full shell plate - but still get +/- .005 to .01mm variances mostly on the higher side of my target COL.

If I press 20 at a time I would typically see:
10 within the acceptable target range (.003)
8 higher than the target range
2 lower than target range

Any recommendations on how I get my COL more consistent? It's extremely time-consuming to measure out each cartridge because it is so inconsistent and re-seat the higher ones to bring them into range.

[ar15barrels]

Measure the length of a handful of bullets and you will find that most of the variance is the bullet nose lengths.
The dies seat from a position on the bullet that is NOT the tip that you are measuring to.
The variation in length mostly occurs between where the die pushes on the bullet and the tip of the bullet.

ALSO, +/- 0.005" OAL variation on handgun ammo won't matter at all.

[Frozenguy]

First-time reloader using a Dillon XL750 set up for 9mm. I'm loading Montana Gold JHP 124GR, Ramshot Silhouette, CCI Small Pistol Primer, and Mixed 9mm Brass.

I got all the dies set up working well but have seen a lot of variance in my COL and seating die. I've tried a couple of things to bring the variance down - i.e. calibrated with a full shell plate - but still get +/- .005 to .01mm variances mostly on the higher side of my target COL.

If I press 20 at a time I would typically see:
10 within the acceptable target range (.003)
8 higher than the target range
2 lower than target range

Any recommendations on how I get my COL more consistent? It's extremely time-consuming to measure out each cartridge because it is so inconsistent and re-seat the higher ones to bring them into range.

What tool are you using to measure this? Model number?

[Clemje]

Measure the length of a handful of bullets and you will find that most of the variance is the bullet nose lengths.
The dies seat from a position on the bullet that is NOT the tip that you are measuring to.
The variation in length mostly occurs between where the die pushes on the bullet and the tip of the bullet.

ALSO, +/- 0.005" OAL variation on handgun ammo won't matter at all.

THIS

Measure from the bullets ogive instead of the tip. I'd be willing to bet your OAL variances are a lot tighter than you think.

I'd HIGHLY recommend buying one of these if you don't have one:

https://www.hornady.com/reloading/precision-measuring/precision-tools-and-gauges/lock-n-load-bullet-comparator#!/

[bsumoba]

Along with variation in the bullets themselves that cause variation in oAL, how the brass is expanded (essentially the neck tension) can cause variation in the OAL as well.

As long as you are within 0.010-0.015 of each other, you're probably ok.

[MarikinaMan]

Measure the length of a handful of bullets and you will find that most of the variance is the bullet nose lengths.
The dies seat from a position on the bullet that is NOT the tip that you are measuring to.
The variation in length mostly occurs between where the die pushes on the bullet and the tip of the bullet.

ALSO, +/- 0.005" OAL variation on handgun ammo won't matter at all.

This. Projectiles are not overly precise when it comes to length due to minute dings and dents in the manufacturing and shipping process. Even the seating die, as AR15B mentioned, can ding the tip.

Loading match rifle ammo, I will get variances, but if I use a measuring tool that takes it from the ogive, I'll be pretty much spot on.

Makes sense?

This is the tool - https://www.hornady.com/reloading/pr...-comparator#!/

[JagerDog]

If you can find a .32 auto casing, turn it upside down on your bullet and measure the combined length with your calipers. Poor mans comparator albeit more difficult to manipulate.

And ya..0.005" is nothing on a 9mm.

[BajaJames83]

That's not going to affect anything that small of a variance probably has more to do with the bullet profile, case variation etc