If the ammo is made in the US to SAAMI specs it'll be labelled 9mm Luger, if it's made in Europe (some Fiocchi and Sellier & Bellot) it'll be marked 9mm Para(bellum) (it'll be slightly hotter - European ammo is loaded to CIP specs) there are some US makers who use just 9mm, and some European brands who use 9x19mm. Surplus stuff could be marked 9mm NATO, or Ammunition, Pistol, 9mm, M882 on the box. Bullet weights range from 95 grain (pretty rare) through 115 and 124 (most common) and up to 147 grain. All factory loads are safe in any 9x19 mm gun that is in good condition. Modern pistols can also shoot +P and +P+ factory loads, but the paper will never know the difference - in fact, there are people who argue that the felon can't tell the difference either.