Have never heard of AP in any NE round. FMJ's do not constitute AP and in fact, depending on bullet configuration and other factors, may demonstrate less penetration than soft point rounds in steel plate.

There is, actually, quite a bit of science involved in AP design. The big NE rounds are pretty much losers in that department, possessing bullets of poor type and too low a velocity for excellent performance.

In addition, think back to the operational demands of countersniping in WW1. After the lines went static, the need for highly accurate rifles with optical sights escalated quickly. Much is made in popular chat about opposing lines of trenches being a football pitch or less distance from each other. This was quite true in some areas but many portions of the lines were much farther apart and in many sectors of the Western Front were not even structured trench systems, being more a conglomeration of shell holes, foxholes and slit trenches. And this last bit was by tactical design late in the war with the brilliant German development of "defence-in-depth". Just SEEING the enemy was a very difficult thing to do, and this does not bode well for Express-sighted rifles of any bore.

Early on the Germans got the jump on the British and French in both identifying the need for snipers, the development of sniper teams {commonly made up of Foresters} and, most importantly for countersniper operations, protection of those teams with hard firing points and visual camouflage in the form of non-linear parapet design.

Bottom line is that an Express-sighted "elephant"-caliber double rifle could not have been more poorly designed for digging out the "Hun". It might be cute to imagine an un-named ex-PWH wrapped up in a sheet of brown Hessian with a charcoal smudged face, Wide Awake hat yanked down close over his eyes and leaning over the top of Piccadilly Parapet "Somewhere in Flanders", changing Fritz's opinions of Deutsches Kultur with 500 grains of Kynoch's best at a {guessed} range of "about" 3-and-a-half rugger pitches but if this ever happened it ranked with winning the Washington State Lottery for odds, and multiple hits for winning the Lottery over and over again.

Unlikely.

The subsequent course of sniper rifle development proves it.