People, especially .45 ACP fans, make fun of the 9 mm. No one makes fun of the 38mm. And the stopping power is pretty good too - a whole lot better than something wimpy like a 50 cal Barrett.
I couldn't find a pic of 38 mm ammo, but it's twice as big around as this stuff and the bullets weigh almost eight times as much. The only drawbacks are the weight of the extra high-capacity bullet clips for my 38 mm AK-47 assault pistol - one or two of the 30-round clips are about all I can handle, and even that is a bit of a challenge to conceal.