Here are a list of firearms you can use:
Walther PPK: James Bond's preferred weapon.
Israeli Military Industries Desert Eagle: A massively powerful handgun capable of devastating damage, one drawback is there is a lot of kickback from the power of the gun, which makes firing in rapid succession almost impossible.
Carbon 15: A rapid fire machinepistol, while able to shoot a lot of bullets a second, the kickback is rather strong due to the rapidity of the fire. Range is rather poor however
Colt M1911: A very popular pistol, a popular sidearm
Glock Series: A semi or Full auto pistol capable of rapid fire, but weak power and the magazines are easily wasted:
Luger P08: A powerful sidearm used by the German Army back in the second World War, capable of good damage, but massive kickback.
Submachine guns (SMG):
Colt 9MM SMG: A moderate submachine gun.
MP5: A very popular Submachine gun produced by German firearms manufacturer Heckler and Koch.
MP7: A slightly larger, more powerful version of the MP5, made by Heckler and Koch. It also comes with a sound suppressor and a scope.
Israeli Military Industries Uzi: a very popular small submachine gun, very useful when dual wielded or as a firearm to replace a pistol, great rate of fire, yet quite poor range
AK-47:The simple, easy to manufacture AK-47 was one of the earliest designs for an assault rifle. Once designed and distributed by the Soviet Union for use by the Warsaw Pact nations, it has become the most widespread, most copied assault rifle design in the world.
Colt M16: a very popular assault rifle used by a lot of countries, it's a very dependable weapon.
FAMAS: An assault rifle used by the French Army.
FN SCAR: A powerful Assault Rifle made by Belgians.
IMI Tavor TAR-21: An assault rifle made by the mighty Israeli Military Industries, famous for the Uzi and the Desert Eagle
M4 Carbine: A popular Carbine used by the American Military.
Double Barrel Shotgun: A popular sort of shotgun, poor range, yet high power, like most shotguns.
Pancor Jackhammer:The Pancor Corporation Jackhammer is a 12-gauge, gas-operated automatic shotgun. It is one of very few fully automatic shotguns, and although patented in 1987, it never entered full-scale production. It has a very rapid rate of fire. The only problem is, this gun is EXTREMELY rare, if you're looking for one, it better be in a museum.
Remington 11-87: A powerful semi-automatic shotgun.
Franchi SPAS-12: The SPAS-12 is a combat shotgun that was manufactured by the Italian firearms company Franchi S.p.A. from 1979 to 2000. The SPAS-12 is a dual-mode shotgun, meaning it can be used as a semi-automatic or pump-action firearm.
RPG-7: A rocket-propelled grenade (RPG) is a shoulder-fired, anti-materiel projectile equipped with an explosive warhead.
Bazooka: Bazooka is the common name for a man-portable recoilless rocket antitank weapon, widely fielded by the US Army. Also referred to as the "Stovepipe", the innovative bazooka was amongst the first-generation of rocket propelled anti-tank weapons used in infantry combat.