Alright, alright...
This is going to kill me to admit but......

You're right.

The story-
I had a good accurate load for my beloved '06 and 180gr Nosler BT's. Problem was at 100yds they were hitting 3" lower than my 165's. The powder was 4350 at 50.8gr.

I reran the OCW on the hi end of the charge (according to Mr. Lyman) and came up with 54.8gr and it's dead nuts on the money flat to 175yds - right even with the 165's. Keep in mind, Mr. Lyman says 50.0 to 56.0 is the useable range for 4350.

At 54.8 I have to run the tumbler on the bench while the wife jiggles the bench top in order to get the powder low enough to start the bullet in the case then, using a 3' long section of 1" rigid pipe on the press handle I can seat the bullet.
I have to shoot them right away before the powder pushes the bullet back out.

With that in mind, now I have to rerun OCW on all calibers for the hi end of the charge. Hopefully I can get at least 3 firings from the brass before I have to super glue the primers in.

I'll try the 15 in the .308.
All the other bullets used in that rifle did so well with either 4895 or 4064 I figured I'd follow suit but- no joy.

I'll let you know how it goes.
I won't rule out the possibility that every once in a great while there will be a type / weight bullet that just doesn't get along with a particular barrel....