gotcha, Your concept of a seater lug being "Just a tube with a rounded mouth..." is a good one. However, you also point out the minor flaw in the concept: the ogive will vary a little from bullet to bullet within the same batch. So unless one sorts the bullets by ogive length the same inconsistencies mentioned elsewhere in this thread will prevail.

"Still like to tinker though." So do I. It appears I will be tinkering with reloading as long as I am able to clearly read the digital caliper and pull the press handle during full length resizing.

I like your new (to me) acronym BTO (Base-To-Ogive) length of bullet.

My new tinker toy arrived yesterday. It is a Redding Big Boss II press. Am I half insane for the purchase? Perhaps, but it will continue my desire to tinker. Actually, there is a method to my apparent madness: I will load identical rounds with the Co-Ax (which has some play in the shell holder and seating die alignment), my Lee Classic Cast Breech Lock Single Stage which has some play in the shell holder and a very slight movement which I can feel but cannot measure in the seating die/breech lock connection, and the new Redding which has a little play in the shell holder but none in the seating die connection. The use of "play" in this context refers to the ability of the cartridge to align itself during bullet seating so it is co-axial with the seating stem.

All of the bullets will be seated using the Redding and Forster Competition Seating Dies, sorted by die manufacturer, and assembled using my usual, consistent routine. Cartridge Base To Ogive (CBTO) measurements will be recorded for each batch of bullets from each of the three presses and from the two Seating Die manufacturers. I am not certain any one of these three press or two brands of Competition Seating Dies will have much ammunition variation from one manufacturer to the other.

Some reloaders will probably enjoy using one press more than the others and might find one of the Competition Seating Dies easier to set up and use than the other. That is a normal selection process. However, my interest at this point is only whether one press or die or combination of press and die will produce more consistent measurements in the reloaded ammunition.

I'll post the results of my experiment here so others may take issue with the results or find flaws in my procedures.

This will be a learning process for me and perhaps, others.