Is there a universal 9mm magazine?

Maglula Universal Pistol Magazine Loader While it is compatible with all 9mm pistols, it also works with 10mm, . 375, . 40, and . 45 handguns.

Do all 9mm rounds fit all 9mm guns?

As we said, you may well run across several different varieties, but as long as you’re using the appropriate ammo and being careful to make sure that you know how to read what’s specific to your gun, you should be fine.