What types of weapons or ammunition won't work with the Siren's Chain Reaction skill?

Question

Maya / the Siren's Chain Reaction skill under the Cataclysm skill tree is described as:

While you have an enemy Phaselocked all of your shots that hit enemies have a chance to ricochet and hit another nearby enemy. Chain Reaction only works with bullets.

What are considered "bullets" by the game?

• Will Chain Reaction work with Shotgun ammunition? (The "Chain Reaction" article on the Borderlands wiki states that "...using guns that can fire multiple bullets at a time, such as shotguns, can result in multiple ricochets at once.") Does this mean that Shotgun ammo are counted as bullets for the sake of the Chain Reaction skill?
• What about Torgue weapons that shoot Gyrojet projectiles or folding fin rockets?
• Thrown (reloaded) Tediore weapons?
• Unique weapons with weird projectiles (like the Sand Hawk and the Unkempt Harold)?
• Legendary weapons that have bouncing or already ricocheting projectiles (e.g. Conference Call, Madhous!)?
• E-tech weapons (especially the SMGs [Plasma Casters])?
• Grenades that shoot bullets (Bouncing Betty grenades)?

Which other weapons or ammo types won't work with Chain Reaction (or will work weirdly with it)?

Answer 1

Orc JMR is pretty much correct; anything that isn't a gyrojet, rocket or e-tech gun will probably ricochet. Shotgun shot counts as "bullets" for the skill (and at least one pellet will almost always ricochet due to the amount of pellets). Elemental shots still ricochet.

Note that not all explosive elemental shots are "gyrojets", as mentioned in that question any explosive gun that shoots "bullets" can cause critical damage and can also ricochet. Torgue shotguns, pistols, some assault rifles and all spiniguns can ricochet. Rocket launchers, grenade launchers, and "torpedo" assault rifles all don't ricochet.

In testing I was unable to get e-tech projectiles to ricochet, which interestingly means that Gaige's Close Enough seems to use a different method of applying ricochet; best I can recall her skill DOES ricochet non-AOE e-tech bullets.

Note that it's never the "ammunition" that's the problem; it's the type of gun. All ammo types (except for Rocket Launcher ammo, because they're always explosives not bullets) can count as bullets, but not all subtypes of a certain gun always fire what counts as "bullets" (mostly due to e-tech and lobbed explosives/gyrojets).

Answer 2

Did some searching and it appears that the following will work with Chain Reaction:

• Torgue guns that shoot Gyrojet projectiles (this includes the legendary weapon, Unkempt Harold)
• Non E-tech shotguns (including Torgue gyrojet shotguns, and the Seraph shotgun, Interfacer)

The following won't work with Chain Reaction:

• Torgue guns that shoot folding fin rockets (different from Gyrojet projectiles)
• E-tech Shotguns (Splatguns or Splasher Blashters)

Info collated from the following Gearbox Software forum posts:

• Maya And My Torgue Fetish
• What types of weapons/ammo won't work with the Chain Reaction skill?