Captain Ryan (Liam Cunningham) keeps a Browning Hi-Power as his sidearm in the film. He wields it during Private Coopers' (Kevin McKidd) Special Ops training. When Sgt. Wells' (Sean Pertwee) team finds the remains of the Spec Ops camp, he picks up one of the Browning Hi-Powers and keeps it as his sidearm for the remainder of the film. Pvt. Cooper also takes one from the Spec Ops camp, but gives his Hi-Power to Megan (Emma Cleasby), who uses it to defend herself. Pvt. 'Spoon' Witherspoon (Darren Morfitt) also briefly handles Cooper's Hi-Power during the interrogation of Captain Ryan. Sergeant Wells later gives his Hi-Power to Cooper during the climax. 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.
Submachine Guns
Heckler & Koch MP5A2
Most of Captain Ryan's (Liam Cunningham) Special Ops soldiers carry Heckler & Koch MP5A2s as their primary firearms. Capt. Ryan's men use their MP5A2s during Pvt. Cooper's Special Ops training. After Sgt. Wells' (Sean Pertwee) team finds the remains of the Special Ops camp later on in the film, the team trades in their blank-firing L85A1s in favor of the MP5s. Most of the MP5s are fitted with surefire weaponlights, and several of them seem to have mid-range scopes installed.
Rifles
L85A1
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.
Heckler & Koch HK91
A Heckler & Koch HK91-A2 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 slimline handguard was fitted, and a block was attached to the receiver behind the ejection port, possibly to act as a brass deflector. The weapon can be identified as an HK91 by its lack of a paddle magazine release lever, and its two position fire selector.
Shotguns
Mossberg 500
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.