Forster Press Bullet Seating Issue

[mclevela]

I have recently purchased a Forster Co-Ax press, great press and I am thoroughly pleased with it.

I have noted seating depth inconsistencies with two different calibers & die manufactures. I have about .004" seating depth variance consistently.
I am using Forster die lock rings and can't see where I am doing anything incorrectly.
The press is new but I have been reloading for many years.

Any help will be appreciated.

Edit: Using Hornady bullet comparator at ogive to measure overall loaded length.
Bullet seating dies used, RCBS & Redding competition seating.

 

[427Cobra]

Are you checking COAL or by Ojive?

 

[mclevela]

I should have stated that, I am checking at the ogive with a hornandy bullet comparator.