G'Day Fella's,

David I would almost bet that your Hornady brass is from Two Different batches or case forming machines/dies. All the cases were then put together, polished, boxed up and sold.
This is standard form, for most Cases and Bullets, that are made by Big Manufactures.

What I would do is, get a Wilson Trimmer Case Holder (The Best Case Trimmer Available!!!) to suit a .458 Win Mag, then hold the cases in the case holder and machine the all the Case Belts, to the same length, front to back!
I thought www.sinclairintl.com may have had them but they don't, you may need to get Case Holder for a .338 Win Mag and use it?
You will need a Lathe to do this and a fair bit of time but I believe in modifying the source of the problem, to suit the Firearm and not the other way around!!!

What ever you do, Don't check the Ogive Length (OL) of a batch bullets from a Big commercial bullet maker, as you might loose sleep over it?
There can be bullets with different "OL", (from 2 or 3 batches/dies), in One Box!

Hope some of the above has been of help!

HooRoo
From
Hammer