Question: is there different size 9mm ammo?
Answer: no , all 9mm is not the same. You should get better answers here soon, but the most common 9mm is 9X19, otherwise known as 9mm Luger , which are the same or interchangeable. THere are lots of different 9mm, 9x18 (soviet), 9x23 (competition mostly) 9mm kurtz a.k.a. . 380.