As promised, here are a couple plugs punched through 3/8 steel plate {support beam section} at 20 meters.

First, before going any further, as I warned earlier, I recommend people not shoot this stuff. I set up a barrier made of tires and a steel plate and had double eye protection, body armor, helmet etc. Good thing too as one large bullet fragment poured back and struck the barrier dead in front of me.

Rifle is a SAKO .375 H&H. Not a .470, .577, etc, but technically a NE I guess, and likely a better plate buster than some others. I chose 3/8 inch plate as I knew the .375 would hole it up close but didn't know at what range it wouldn't.

Please note, I do not know what the alloy of the plate is. This makes all the difference. Every piece of metal is different and depending on plate thickness, alloy and heat treatment, results can vary completely. As stated before, there is a science of armor busting and I do not make any claims to settle anything in this little demonstration, except to show what happens in this specific medium.

Standard Boards/Jugs media backing up steel plate {for recovery}. Here are the results of two shots fired at muzzle velocity 2450 fps:

Left 3 pieces:

300 grain Hornady FMJ; Full penetration 1 board, found in first jug. Bullet hole thru plate just under 5/8 inch diameter. Pieces found in the jug were the steel plate plug and the rear half of the jacket. This is the narrow diameter "tube" seen. Rifling is clearly distinguishable on the inside of the tube, the jacket having reversed itsefl inside out like a sock. The wider tube is the portion that bounced back and struck the barrier in front of me.

Right 3 pieces:

300 grain Hornady Round Nose Soft Point. Full penetration 2 boards, found in 2nd jug. Bullet hole 5/8 diameter. Pieces found in 2nd jug were the piece of lead and the BASE of the jacket, flattened and showing rifling. Steel plug waas found on the table, HOT.

Yes, the soft point penetrated deeper than the FMJ. Commonly happens in some media. Remember, neither of these are AP rounds.

Soft point did not penetrate the plate at 100 meters or 200 yards {distances on my range}. Divit at 100 was fairly deep and planting a few shots in the same area would likely be enough to allow one to get through after a time.

A small demonstration to show the effects of a vintage 1912, pre-War round on relatively soft plate. That Hesketh-Pritchard went no further with use of NE rounds for "loophole busting" does not surprise me.

A couple further pix:

The table after the Hornady 300 grain FMJ shot {piece that bounced back placed on the bottom right for display}:

The table after the Hornady 300 grain Soft Point shot {Wolf 60 grain FMJ 5.45x39 shot above the black dot}: