COL varies widely

[flashotter]

I was reloading 115gr 9mm plated (Everglades) in supposedly once fired brass in my Lyman single with Hornady die, COL of 1.135. Kept getting COL difference from 1.121 to 1.145 almost from one round to the next. Had to back off each time to avoid having to frequently use bullet puller hammer, very time consuming and frustrating. What would cause this to happen? Usually the depth stays constant or varies no more than a couple thousandths either way. Im thinking a variation in brass or bullet length but COL should be the same as actual depth would vary instead right?

[divingin]

Brass length won't affect OAL. That's set by the seating stem to case holder distance (i.e. with the ram fully up, the bullet should be seated to specific OAL regardless of whether the brass is half an inch or a full inch long.) Take a look at where your seating stem contacts the bullet, and look for differences between there and the bullet nose.

If you're running a lot of interference fit, it may be due to press stretch, but I would tend to put that way down the list. I'd put an incomplete handle pull above that.

Edit: Does the COL difference have an effect on accuracy or function? I'd suspect it wouldn't.

[bergmen]

Never had this happen in 30 years of reloading. Make sure everything on your die is tight and not loose.

Dan

[smoothy8500]

I was reloading 115gr 9mm plated

Most likely some variation in the nose where the seater contacts the projectiles. Generally, the seater contacts the curve or ogive of the projectile-not the tip.

You have confirmed projectiles are all the same length by measuring at least a handful right?

[TomReloaded]

It's the combo crimp/seat die. It's likely misadjusted.

Honestly, the combo die kind of sucks. I'd get separate seating and crimping dies.

[Sandspider500]

Try it with the same headstamp brass.

[JagerDog]

Is the seater insert clean?

Try to obtain a case (maybe .32), invert on the bullet and measure the combined length of cartridge and inverted cae. See if your variance comes down substantially.

[JagerDog]

It's the combo crimp/seat die. It's likely misadjusted.

Honestly, the combo die kind of sucks. I'd get separate seating and crimping dies.

Nah

[ar15barrels]

I was reloading 115gr 9mm plated (Everglades) in supposedly once fired brass in my Lyman single with Hornady die, COL of 1.135. Kept getting COL difference from 1.121 to 1.145 almost from one round to the next. Had to back off each time to avoid having to frequently use bullet puller hammer, very time consuming and frustrating. What would cause this to happen? Usually the depth stays constant or varies no more than a couple thousandths either way. Im thinking a variation in brass or bullet length but COL should be the same as actual depth would vary instead right?

Bullet length variation because some bullets are longer FROM where the seating die is pushing on the bullet.

Also, if you are seating and crimping in a single die, the cases that are longer will dig into the bullet more and that will make those rounds end up longer as the bullet will get a groove pushed into it by the seater.
Separating seating and crimping will usually get you more consistent OAL's because the crimping will not be a factor in the seating.
Separate seating gets rid of the bullet getting crimped while being seated so now the bullets will be seated more consistently.
Then the crimping is done as a separate step so that the seating will not affect the crimping.

[flashotter]

Thanks for the input, I decided to seat and crimp separately, so I ordered a Lyman Brass Smith 8 turret and dies from Midway. I think maybe there's something wonky with the Hornady seat/crimp die.

['ol shooter]

The only crimping you should be doing on an auto-pistol case is to remove the case mouth flare, not any more. Squeeze the case and it springs back, lead does not, now you have a loose bullet in the case. Save your money, adjust the seating die until the case is flare free and you are good to go. As was stated, the seating stem is locating on the ogive, any differences in bullet profile will change the OAL, but the bullet will still contact the feed ramp in the same place (the ogive) as all the others.

[bruce381]

as above try some they will shoot fine but yeah get separate seater and crimp dies.

[BrassCase]

Thanks for the input, I decided to seat and crimp separately, so I ordered a Lyman Brass Smith 8 turret and dies from Midway. I think maybe there's something wonky with the Hornady seat/crimp die.

I have that Lyman press for rifle and for pistol cartridge development, I like it, Before I got a Dillon I made several thousand pistol rounds with it and all my rifle. I can set up both the 308 and 6.5Cr on a single turret. I have 3 turrets now and want another.

[flashotter]

Yes I set it up and made some .38's, very happy with Lyman products.