Yeah, the only thing tok FMJ is good for is body armor penetration. I mean, that was the whole point, right? But nowadays we want expansion (to get bigger bullets out of smaller packages so we aren't all forced to carry 45s), and you need energy (i.e. velocity) to dump into deforming the bullet. Tok HP is very much a modern round; being an older cartridge "magnumized" into a high pressure, high velocity expansion round (again, basically a .30automag)
FNH probably would have used it in the P90 if they didn't think they'd get more money by making their own cartridge (bet H&K was thinking exactly the same thing!
). It's not the gun cost that gets ya, but the ammo