Smellie, your post just reminded me of the round nose, 160 grain Swede surplus bullets, with the exposed lead bases, that were once available and cheap. They had cupro nickel jackets, which were quite malleable.
I used to shoot these out the the now gone Carcanos I owned, chambered for the 6.5x52.
Back in the day a bunch of surplus 6.5x52 Carcano ammunition came into International Firearms out of Montreal. It came out of Finland with a bunch of other surplus ammunition back in the late seventies. It wasn't very reliable ammo. Lots of Verdigris on the cases and in the twelve round boxes. It was all on six round enblocs and pretty much a mess. I just happened to be Johnny on the spot and was offered the 12k lot of ammo in wood crates, if I would take it with me when I left. Of course, I complied.
I washed it all in a bath of Sunlight detergent, laced with vinegar. It all came out bright and shiny but the corrosion had gone to far. Even for me, the cases and primers were to badly scored to want to attempt to shoot it.
I pulled every one of those bullets and salvaged the powder, which fits the description of the original powder you described from the 1908 Text Book of Ammunition.
Much of the ammunition, back at the time that book was written, was a clone of the original Rottweil, double base, flake powder that was used to replace Black Powder. Rotweil licensed all sorts of nations to produce this powder and Italy was one of them.
You're right, that powder is fast. It was first produced for cartridges with large diameter, heavy lead bullets, then along came France, using a very similar powder and loaded it in their very good 8mm Lebel around 1886 and used the same powder all through WWI, into the twenties. Why change it, if it isn't broken.
Anyway, I sold off all of the bullets long ago, but I still have the powder from those old Finn cases. It's great in cartridges like the 45 Long Colt and 455 Webley and even the 380 Webley Short.
What I did back then, because 6.5x52 was always difficult to come by in shootable lots or decent condition, was load up this double base flake powder to the same load of 30.4 grains, which was the average weight of the charges from the scrapped cases.
This load performed very well out of my rifles. The exposed lead bases were pushed up into the jackets, forcing them to obturate enough to fill the grooves. Which is exactly what you were doing with the Remington flat base bullets.