Please help with seating issues

[ABL_ZA]

Hi,

I need some help, I don't know if I am doing this all wrong.

Information
Reloading with - 143gr ELD-X, 41.4gr Hodgdon 4350, virgin Lapua brass, CCI 450
Reloading on - Forster Co-ax, Forster micrometer seating die, APW expander mandrel (.264)
Reloading for - Tikka T3x 6.5 CM

Problem
I seat the bullets using CBTO as my final measurement of 2.19

The problem is all my bullets differ in length between 1.4295 - 1.436 with around 90% being within 1.431-1.4335 (0.0025 difference).

This means all my bullets get seated differently in order to get the final measurement for CBTO of 2.19. You have to seat longer bullets deeper?

Does this make a significant difference? It's been a nightmare measuring every round of ammo after seating to get consistency, and even then, I seem to have an overall result of of 2.1885 - 2.1905 sometimes after multiple seatings and re-measurements

I assume:

• I am doing something wrong/dumb, or is this just an acceptable difference

 

[WeiserBucks]

.002" difference in CBTO is essentially meaningless.

 

[ForgeValley]

I assume:

• I am doing something wrong/dumb, or is this just an acceptable difference

Your 2nd assumption is correct. If you want to go down the rabbit hole, go over to accurateshooter and search cbto variance. Be warned, you'll be sorting bullets and implementing a multi-step seating process.

 

[ShtrRdy]

Did you check to see if the bullet tip is bottoming out on the seating stem?

 

[BuildingConceptsllc]

Check your seating die stem and make sure it is fitting the bullet correctly. The variation and chasing that consistency leads to bullet sorting , as has been said. Your variation seems like too much.

I went that route for a while , sorted bullets in fishing tackle trey type boxes. Then at some point I just decided to buy the most consistent bullets I could and get my seater to fit it well and roll with it. I'm very happy with my choice. Of course finding the bergers you want can be a real pain if you don't buy large amounts when you can. Hornadys are a lot easier to find.

 

[JM4590]

Put bullet to paper….and I believe you will answer your own question

 

[Dave62677]

You can switch to CNC machines solid copper bullet.

 

[acourvil]

You would have to check your lot of bullets to be sure, but most of the time the BTO variance is less than the OAL variance. So seating depth wioll be more consistent, even if OAL varies more. Unless the OAL variance is creating problems due to mag length, I would focus on BTO and not worry about the OAL variance.

 

[918v]

.264” expander mandrel is way too big