Back in an age of Disco, revolvers in police holsters, and 8-track tapes...everyone in my military unit routinely used copious amounts of spray WD-40 (the old stuff) on all of our weapons and metal equipment.
It was a standard ingredient for cleaning parties after coming in from the wet and rainy field. It got applied to mortars, machine guns, pistols, rifles, shotguns, radio bodies, binoculars, recoilless rifles, crew served gun sights, bayonets, knives, entrenching tools, submachine guns, night vision devices, etc. We used it by the pallet load.
The little mini-cans were carried in rucksack kits for cleaning while occupying patrol bases in the field.
We never considered it as a lube, but rather as a water displacing cleaner and coating. WD-40 was sprayed in all nooks and crannies and also applied with a rag to all metal surfaces after initial cleaning with either hot water or a solvent (usually issue Rifle Bore Cleaner but often spray carb cleaner). This would be followed by generous application of LSA military gun oil (later superseded by CLP).
End result (properly applied) = no rust. Ever. The punishment for allowing a rusty weapon was severe and usually extended to the group...thus insuring that leaders and peers ruthlessly inspected all weapons.
This was SOP in the Coastal Pacific Northwest with generally constant rain, snow, humidity, or salt water exposure. WD-40 also worked well in the southwestern deserts of the US, the bitter winter cold of the Great Lakes region, the coastal surf zones of California and Florida, the swamps of the SE, and the jungles of Panama.
My M1911A1 was often carried for days (or even weeks) inside a wet leather holster while in the field. The pistol was liberally coated (inside and out) with WD-40, with actual lube applied on the appropriate moving surfaces. No rust.
We didn't "know" that you shouldn't use WD-40 on weapons. Somehow our weapons managed to work despite years of spraying WD-40 onto them.
On the other hand, once CLP came into widespread use, I pretty much quit using WD-40 on mil and personal weaponry, because CLP did it all. I participated in the Army's testing of CLP under rather extreme conditions and became a personal convert to its use (to this day).
For me, WD-40 is reserved for cleaning personal weapons which have been dunked in water or become rain soaked. Even then, its just something to use during cleaning, with the excess getting wiped off prior to being replaced by CLP.
I HAVE ZERO EXPERIENCE WITH THE NEW PRODUCT.