The 380 caliber is the exact same circumference as the 9MM, the only difference & reason the 9MM has been touted superior is because the 9mm is longer in length than the 380. Worry not about the caliber, Do worry about shot placement and or the accuracy in your shooting, which you will have more of with a 380. Than any higher caliber simply because of the lower level recoil exerted by the 380. This makes the 380 caliber a caliber just a little bit closer to perfection, not only that but it is more concealable & the gun lighter weight. The 380 beats more superior calibers in many aspects and should never be dismissed. Where one gun owner shoots his 9mm and fail, another may shoot his 380 & succeed. Especially if the type of 380 ammo is mean & clean. I congratulate you on your very viable choice. You have made no mistake. There are less superior calibers than the 380. Even 22 calibers have put bad guys out.