The Browning Hi-Power is used many times throughout the film, first by Captain Ryan (Liam Cunningham) during Private Coopers' (Kevin McKidd) Special Ops training and later shown to be Sgt. Wells' (Sean Pertwee) sidearm. Later in the film it is used by Megan (Emma Cleasby) and is finally used by Cooper. An interesting point is that Ryan's pistol has no magazine in the gun at the start, yet somehow he manages to chamber a round and kill a dog without the slide locking back. Although there was no magazine in the gun to lock the slide back, it does raise the question of how he managed to chamber the round in the first place. Not to mention Mark III Hi Power's have a magazine safety, which means even if there was a round in the chamber, he couldn't have fired without a magazine in place.
The Heckler & Koch MP5A2 is first seen during Pvt. Coopers' Special Ops training and are later taken from the Special Forces camp. Most are seen with a Surefire light and at least one has some kind of scope or laser sighting mounted on it.
L85A1's are used by the British Army team during the training exercise at the start of the film, with military blank adapters and SUSAT sights attached. They are later ditched when the team discover the dead Special Ops team, as they would be useless against a real threat.
A Heckler & Koch G3A3 is another weapon taken from the Special Forces camp and used by Private "Spoon" Witherspoon (Darren Morfitt) and then by Private Terry Milburn (Leslie Simpson) after swapping his MP5A2 for it. This weapon later disappears from the film, without explanation. The rifle used in the movie had difficulty handling blanks and the bolt had to be manually cycled occasionally. It seems the flash hider was removes from the gun.
A Mossberg 500 shotgun is taken from the Special Ops camp and is used by Pvt. Joe Kirkley (Chris Robson) throughout the farmhouse attack and escape from the forest. Many times throughout the film it is shown firing way more rounds than the real gun can hold (in the typical action movie style).
Used by the team against the werewolves. They are not seen taken from the Special Forces camp, so it's possible they could have been taken with the team for the training exercise. Help identifying the kind of grenade used would be greatly appreciated.
