.223 bullet seating depth variations


October 27, 2009, 06:17 PM
Every round I load has a different OAL. Sometimes it's up to .02 off from round to round. Measuring from the tip to the bottom of the case using calipers. I understand it seats from the ogive on the bullet but can this change that much from round to round? Not sure how to accurately measure that.

Using a Rockchucker press and Lee bullet seating die. I've tried screwing in the die a little further, tightening the lock nut with a pliers, and measuring the bullet length prior to loading. The bullet adjustment knob wiggles a little and I'm wondering if that's normal.

Last night I was trying to load at 2.232 using 55gr Sierra FMJBT gameking bullets and out of the 20 I loaded there was a spread from 2.21 up to 2.233. Hornady Vmax, Nosler BT, Remington SPS bullets, they all vary allot from round to round.

Loading 9mm it is dead nuts every round.

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October 27, 2009, 07:00 PM
The variation in gross OAL is not unusual, especially with FMJs - very poor tip uniformity.

You should measure from the ogive with a tool such as the Stoney Point device now sold by Hornady.

October 27, 2009, 07:21 PM
I'm more than a bit surprised by the .023 with the Nosler Ballistic Tips & Hornady V-Max!

October 27, 2009, 07:22 PM
9MM-exact-.probably all other STRAIGHT wall case-exact. The bottle-neck case of a .223 will vari in length. Did you trim all your brass to exact length? Are all of your cases of the same mfg. and times shot? Unless you're Bench Rest shooting .002-.003" is not going to make a difference on your groups. Don't "Beat Yourself Up" on your handloads:banghead:=they will probably be GREAT:D

October 27, 2009, 07:36 PM
"The bottle-neck case of a .223 will vari in length."
I understood him to be talking about OAL.

October 27, 2009, 07:41 PM
What LEE die set do you have? A variation of .005" to .010" is normal. Your is to much as you know. From Lees website. Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

October 27, 2009, 07:49 PM
You do not need to crimp, your choice. Just dont screw the die in to far. http://www.leeprecision.com/cgi/faq/index.cgi Seating die crimp style

There are two crimp shoulders in our bullet seating dies. The first shoulder applies a slight taper crimp and the second shoulder applies a full roll crimp. The closer the die is adjusted to the shell holder the heavier the crimp will be.

October 27, 2009, 09:29 PM
Drill a 7/32" or 13/64" hole in a piece of steel, place the loaded round bullet first into the hole(upside down). Now measure the difference between the rounds(I use the rod that extends out on my caliper). This does not tell you the OAL, but will show if your die is seating the bullets to different depths. By the way this is a poor(or cheap) man's bullet comparator. Really the hole size does not matter as long as it is small than bullet diameter and larger than the bullet tip ....anywhere along the ogive.

Jimmy K

October 28, 2009, 09:58 AM
The die set I have is the Lee Deluxe three die set. I'm not crimping them as it's for a bolt gun.

Don't reload for competition but I'm an obsessive perfectionist. The bullet comparator sounds like exactly what I need. Making the perfect round is as enjoyable to me as shooting it.

Sounds like the Hornady set is the best buy unless there is a better recommendation? THR rocks.

October 28, 2009, 02:49 PM
ochadd quote: ...but I'm an obsessive perfectionist

While this trait is often irritating to those around you, it is beneficial for someone who reloads.
That's the way I see it anyway.


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