Depending on the difficulty you play on, ammo can be very scarce in Resident Evil 2.
Thankfully, you can make more ammo for the guns you like the most by combining gunpowder that you find on your exploits.
There are two types of gunpowder to find in Resident Evil 2: standard and high-grade. You can also find large variants of standard gunpowder that make twice as much ammo.
To make ammo with gunpowder, all you need to do is combine it in your inventory. When playing as Leon, combining two standard gunpowders will result in handgun ammo. Combining standard and high-grade gunpowder will result in shotgun ammo. Combine two high-grade gunpowders to make magnum ammo.
Like Leon, when playing as Claire, combining two standard gunpowders will result in handgun ammo being created. Combining standard and high-grade gunpowder, however, will result in acid rounds being created for the grenade launcher. Combining two high-grade gunpowders will create submachine gun ammo.
Use the gunpowder you find effectively and you’ll be able to use your favourite weapons quite often in Resident Evil 2. You’ll probably still find yourself having to switch between them from time to time though, especially if you try to fight every enemy you encounter.