When you open a Gun Mettle Case you have a small chance of obtaining an 'Unusual Weapon', and a rarer chance of getting a 'Strange Unusual Weapon'. Any weapon normally available from the Case can be Unusual. These weapons are very special, because they have particle effects associated with them!

The Gun Mettle Update introduced 4 different effects; Isotope, Energy Orb, Cool, and Hot.

The effect is associated with the 'barrel' of the weapon and is visible in DirectX 8, but the skins are not.



Description: A green glow, brightest at the end of the barrel fading out quickly so that only the end quarter to half of the barrel has the effect. Green rings surround the barrel and move quickly along the barrel towards the user. Sparse green spherical particles rise from the barrel. A short trail of green gas rises up from the end of the gun barrel. Nothing is present inside the barrel.

Praises

• High visibility effect
  
• Leaves a short 'gas' trail
  
• A must for fans of Lime paint!

Criticisms:

• The smallest effect
  
• No glow from within the barrel

Description: Red and orange rings spiral from the end of the barrel back along the length of the barrel becoming pale blue as they approach the user. An intense red/orange glow emanates from the end of the gun barrel.

Praises

• The biggest effect, covering almost the entire gun barrel
  
• Bright glow within the gun barrel
  
• Plasma colors complement the team colors very well

Criticisms:

• No mist, no rising/falling particles
  
• Not the most visible effect

Description: A blue mist surrounds the gun barrel and slowly falls, turning paler blue as it does so. Ice cubes and snowflakes fall from the barrel. The centre of the barrel glows blue.

Praises

• Aesthetically pleasing blue glow from barrel
  
• Lots of falling particles, especially on long barrels (e.g. sniper rifles)

Criticisms:

• Lots of falling mist might be distracting to some
  
• Possibly best suited to the Blu team
  
• Cold is not normally associated with guns

Description: A red haze surrounds the barrel, gently rising upwards and becoming paler as it does so. Small glowing 'embers' can be seen rising in the haze, primarily eminating from the end of the barrel. The centre of the barrel glows red hot.

Praises

• Well suited to most weapons, especially Flamethrowers
  
• Red hot glow from barrel of the gun

Criticisms:

• Lots of rising mist can be distracting to some
  
• Arguably best compliments Red team players
  
• Not always very visible

Compared to the size of the Rocket Launcher, the isotope effect is small, only covering ~25% of the length of the launcher. Cool and Hot both look great and cover ~50% of the length. Energy Orb looks awesome; facing the launcher you see a red-hot glow emanating from the end, and the red/orange/light blue energy pulses down ~75% of the launcher.

The Sniper Rifle's long barrel is perfect for showcasing unusual effects. The Cool effect looks amazing, as does the spiralling Energy Orb. Hot and Isotope could be distracting, and having a bright green glowing 'here I am' marker on your gun might attract unwanted attention.

Unusual scatterguns are relatively uncommon since they are only available as Commando Tier (the Night Terror) and Assassin Tier (the Current Event). Of these the Current Event will probably be the most in demand because of the electric purple color. Effects-wise, the Scatterguns have quite large effects thanks to the relatively broad double barrels. Isotope is quite fitting for a class that loves to get in close and cause havoc among the enemy ranks.

I must say I'm a little disappointed with Hot, Cool, and Energy Orb effects on the Scattergun. The effects have been designed for single barrel weapons, so the inner barrel glow that I love is hidden between the 2 Scattergun barrels.

Effects on the Medigun have to compete with the medibeam particles and full ubercharge particles for visibility. E.g. If you predominantly like to join the Red team consider Cool or Isotope for contrast, or Hot/Energy Orb for complementing colors. Isotope does look great on the medigun; it contrasts both team colors and leaves a nice green 'gas' trail.

On Miniguns the Energy Orb effect is almost perfect. It's big, it spirals (matching the miniguns spin), and it is visible the length of the gun. The isotope effect, though small, fits very nicely on the end of the minigun providing great visibility. Hot is also excellent on miniguns, cool maybe less so.

Hot is the natural choice for Flame Throwers, and it looks great. Cool is a little 'unusual' but has a very noticeable effect thanks to the Flame Thrower's long barrel. The long barrel is also a boon for the Energy Orb effect, which as always is unobtrusive and great looking. The red hot glow of Energy Orb pairs well with the Flame Thrower. Isotope is high visibility but just doesn't look right on a Flame Thrower.

No stealth needed for Demoman, so big bold effects are welcome. The Isotope effect again leaves a gaping black hole in the barrel of the launcher where a bright glow would have looked good. Isotope does, however, match the glow from the Demoman's eye upon claiming a head, so it does have that going for it. Hot and Energy Orb both look great. Cool is masked a bit by the stickybomb launcher's 'ammunition barrel'.

Shotguns have a few points going for them; (1) The Shotgun Skins from the cases are both awesome; (2) They have long barrels and therefore more pronounced effects; (3) They can be used by 4 classes (Soldier, Pyro, Heavy, Engineer). Since shotguns are a close to mid-range weapon of last resort it's good to have a gaudy effect that says 'don't mess with me, I'm a pro'. To this end Isotope is great. Also good are Energy Orb and Hot because your enemy will inevitably be staring down a red-hot glowing barrel. Cool, to me, is the least desirable shotgun effect since it doesn't quite have that close-range scare factor.

A relatively small weapon with long barrel, which means the effects really take it over. As with the Sniper Rifle, having a bright green marker on your gun when playing as a class that relies on stealth might be a bad idea. I think Energy Orb looks great, but the fog/mist that surrounds the Cool or Hot weapons pairs well with Spy's stealthy character.

Fairly popular as a secondary, and available to Scouts and Engineers. The mist from the Hot effect might be a bit of a distraction.

So far SMGs have been the cheapest unusual weapons, likely because they are relatively common Mercenary grade weapons and because they are not popular secondary weapons for a class that rarely needs to use a secondary weapon. However, all effects look great on SMGs! Cool and Hot engulf the entire weapon; energy orb covers the length of the barrel; and isotope remains highly visible.

All the 'World Model' Images were captured using a modified 'Inspect' panel from the TF2 in-game Backpack viewer. I own several of these items and simply used the TF2 'Particle Editor' to switch between effects. Some of the items I do not own (Shotgun, Scattergun, Stickybomb Launcher, Revolver), and in these instances I switched out their models with an unusual weapon I do own. This isn't ideal, as Gun Mettle skins are generated in a rather complex way. As a result the skins on these items do not reflect the actual appearance of the weapon. The effects on those weapons though, are accurate depictions.

Some people have said that in-game the effects don't look as good as in these pictures. That is most likely due to the fact that these weapons and effects are displayed on a black background and with a single light source (other than the particles) to showcase the effects. Also note that these are static images, and in-game the particles are dynamic. Energy Orb in particular pulses with bright and not-so-bright spirals of light. A still image here may have captured a particularly bright stage in the particle effect.