Others have perfectly covered what the Glock uses, but I'll just add, that almost all references of modern guns being chambered in the 9 mean 9X19 Luger.
The only ones you'll probably consider using are the 9X17, 9X19, and 9X25.
The 9X17 is almost always referred to as the .380 and the 9X25 Dillon is a very fast round that can be used in 10MM guns with the appropriate barrel change.
IIRC, the 9X21 is a 9MM designed for Europe where "military calibers" are often outlawed (9X19 is a NATO standard round). The 9X23 Largo is an old caliber originating in Spain, and no longer used much. The 9X18 Makarov is a Russian round also not very popular. Out of the East Block rounds, you'll probably encounter the 7.62X25 Tokarov more often. There are also a couple of others. I think Winchester or Remington experimented with a 9X23... don't know if they had any success.
Note that the bullets in many of these rounds are slightly different. They vary in weight, shape, and diameter.
The only ones you'll probably consider using are the 9X17, 9X19, and 9X25.
The 9X17 is almost always referred to as the .380 and the 9X25 Dillon is a very fast round that can be used in 10MM guns with the appropriate barrel change.
IIRC, the 9X21 is a 9MM designed for Europe where "military calibers" are often outlawed (9X19 is a NATO standard round). The 9X23 Largo is an old caliber originating in Spain, and no longer used much. The 9X18 Makarov is a Russian round also not very popular. Out of the East Block rounds, you'll probably encounter the 7.62X25 Tokarov more often. There are also a couple of others. I think Winchester or Remington experimented with a 9X23... don't know if they had any success.
Note that the bullets in many of these rounds are slightly different. They vary in weight, shape, and diameter.
