The opening post on .380 to 9mm Mak is about "Forget the cost, would it be worth it to make the conversion, from a defensive ccw point-of-view, in terms of terminal ballistics??"
Lone Wolf's major selling point for their $140 conversion barrel is you can use cheap combloc steel cased 9mm Makarov ammo in your familiar Glock 42 or Ruger LC380 without paying $400 for a new gun. To me that's the only selling point for the conversion, cheap target practice: you can save more than the cost of a conversion barrel in cheaper ammo in one season.
Common off the shelf loadings are:
.380 ACP, Federal Cart. Co., 95gr FMJ, 980 fps, 203 ft/lb.
9mm Makarov, C.I.P. standard, 95gr FMJ, 1050 fps, 231 ft/lb.
9mm Luger, Federal Cart. Co., 115gr FMJ, 1180 fps, 355 ft/lb.
Looking at energy standard ammo commonly available in commerce on a scale of 9mm Luger = 20, .380 is an 11.4, 9mm Makarov is a 13.
Lone Wolf's lesser selling point is that there are defensive loads for 9mm Makarov that are better than standard .380 or 9mm Mak. That gets into the fact there are also defensive loads for .380 better than standard 9mm Mak. 9mm Luger still tops them.
BTW the LC380 is the 380 version of Ruger's LC9 9mm, it is not the LCP which is a smaller pistol. Ruger makes a 9mm Luger LC9 Conversion Kit for the LC380 if one wants mild 380 for practice and 9mm for carry in the same gun.
https://ruger.com/micros/LC9Conversion/index.html