almost) it breaks into 2 full length segments at impact, creating 2 diverging wound tracks. the segments, being unstable, "yaw' as they pass thru the animal or man, creating massive damage and shock.
I could not get solid aluminum (rod, turned on a lathe) to expand reliably in a "full flower' manner as jhps do. But a large nose cavity DOES apply enough lateral force to break apart the bullet as described (at such velocities).
It's just a question of using an Exacto saw to slit the bullets ever deeper as you test fire the loads, until you get reliable breakup of the bullet. then use a milling machine and .008" thick slitting saw to get a precise cut. You have to make a "holding block" for a row (mine holds 6 bullets) in the milling vise. and the vise of course has to be precisely aligned with the table's axis (the one you are using to make the slits in the bullets).
70 grs at 2300 fps (allow commander, 460 Rowland chamber and cases) is almost 800 ft lbs, less recoil than .45 ball, and both segments get a reliable 8-9" of penetration in animals. They go down as if hit with a 223 rifle softpoint.
this slit does hurt accuracy a bit. So does making the bullets on a lathe. but I get 10" groups at 50 ft, which is plenty accurate enough for justifiable civilian defensive work. I'd settle for half that much accuracy, if I had to, in order to get this same amount of shock and tissue destruction. :-)