Hypothetical weapons with debatable usefulness that employ the various quirks of quantum physics.

• The Uncertainty Gun. The more accurately you aim your weapon, the less damage it does to the target.
• The Observer Gun. Observing a system causes changes to occur, thus, observing your opponent after shooting them will cause them to no longer be shot.
• Schrödinger’s Gun. Targets hit by this weapon are both simultaneously dead and alive, and only by checking to see if they are shot will they confirm their death.
• Quantum Tunnel Gun. An actually useful weapon, the QTG can fire a projectile through matter to hit targets behind, or, it can be used to simply ‘tunnel’ through the air and thus extend the range of a projectile, or be used to fire at nearer targets and conserve momentum by negating speed loss over distance.
• Time Paradox Gun. This weapon only works against enemies you have already killed. Bullets are fired back in time and kill your enemies before you shoot them – thus, in the present, you need to fire at already fallen enemies. Failing to do so will mean that they never get shot in the past, and thus, they will no longer be dead and will rise up to continue to fight.
• Entanglement Gun. This weapon does not fire bullets, instead, it fires the idea of a bullet. This entangles itself with the bullet in an enemy’s weapon, transferring all directional momentum and thus sending their bullet flying backward through their weapon and into them.
• Superposition Gun. Utilizing particle-wave duality, this weapon maximizes ammo conservation by translating projectiles to a waveform, firing them through a series of splitters and through a membrane where thanks to the observer effect and quantum consciousness bias, the waveform replicates and amplifies itself before each copy then collapses back into multiple projectiles. Bullets for free, baby.
• Paradox Rifle. This gun only works if it is never fired. It is the most precise weapon in human history, as long as you never aim with it. Bullets are unlimited, as long as nobody knows a) how many its clip holds and b) how many it has fired so far. Thus, this weapon can potentially destroy all of humanity, but seeing as humans still exist, the weapon MUST have been fired and failed, otherwise if it was never fired we would all be dead.
• Spaghetti Gun. This weapon fires spaghettified projectiles at an enemy. However, the moment they are fired they lose velocity, thus no longer being spaghettified and thus gaining mass. The further the projectile travels the more massive it becomes. The applications are practically limitless.