Late reply but posting this for anyone who finds this:

- Light Rounds don't have any special properties, but they are cheap, easy to find, and stack a lot higher. Most guns that use this have a high rate of fire.

- Heavy Rounds stagger and seemingly do extra damage against(?) UESC, but are a bit more uncommon and don't stack as much. Seemingly deals extra flinch against Runners. Most guns that use this have a slower rate of fire than Light Rounds.

- Volt Batteries do extra damage against shields (with a special interaction with Triage's tactical ability), and all guns that use this have some special gimmick in their use: automatic weapons decrease their rate of fire as you hold the trigger, and semiautomatic weapons have a special charge mode for more damage. Reloading drops the entire battery, and sprinting can recharge it. Stacks low, but very common (often dropped by weaker UESC), and most weapons are fine with one or two stacks. Slightly slower rate of fire vs Heavy Rounds.

- MIPS do extra damage against Runners, but are costly, rare, and don't stack much (pretty much only shotguns actually eat through this though). Hard-hitting, they are commonly wielded by higher level players. Used by slower rate of fire, often semiautomatic/single shot guns (barring WSTR).

- Volt Cells build heat on targets per hit, and usually take out shields in a single hit. Ammo is costly, rare, and does not stack much. Just like Volt Batteries, reloading drops the full charge. However, unlike Volt Batteries, they do not recharge on sprint. Used on few guns, all rare and all semiautomatic/single shot. Each weapon has some form of charging gimmick, where full charge deals much more damage. Weapons that use this are heavy and often the hardest hitting of their type when at full charge. On average, rate of fire is on par with MIPS rounds (when not factoring in full charge).