Lehigh defense makes a solid copper .32acp bullet thay they also load into .30 carbine. It's not a fully rounded/turned profile like the THV bullets, but the gel testing that has been posted on youtube seems to support your supposition that a less rounded profile provides more penetration and a deeper overall wound profile.
Seems that they now offer a .311 diameter extreme defense bullet now.
I really need to get an m1 enforcer pistol.
>not its own parent case
Correct. It's a 9x23 case loaded with a 9x19 bullet to keep 9x19's OAL. Whole point is the same as .460's case. The extra brass length isnt needed, it just prevents you chambering and firing a .460/.960 in the lower pressure chamber of a .45acp/9mm luger weapon.
The load development I have seen seems to be erring on the very conservative, with carefully taking into account the OAL of different "9x19" bullets to maximize powder volume while managing the case pressures.
Shell shock cases are currently only offered in 9x19, but they are being touted as capable of withstanding much higher chamber pressures. Thinner walls allow for higher case capacity as well, which I think makes a 9x23 case (or if they offered a 5.56x45 case next) would be an excellent 960rowland case.
Even higher chamber pressures could help to push a light solid copper bullet into .357sig velocity territory, while still being able to shoot normal 9x19.