Bonus Weapons:

Complete the indicated task to unlock the corresponding weapon bonuses.

Bolt Action Rifles

Springfield: Reach level 4.
Sniper Scope: Already available.
Bayonet: Complete Marksman Challenge 1
Rifle Grenade: Complete Marksman Challenge 2.
Arisaka: Reach level 4.
Sniper Scope: Complete Marksman Challenge 1.
Bayonet: Complete Marksman Challenge 2.
Rifle Grenade: Complete Marksman Challenge 3.
Mosin-Nagant: Reach level 21.
Kar98k: Reach level 41.
PTRS-41: Reach level 57.

Rifles

SVT-40: Reach level 4.
Flash Hider: Complete Marksman Challenge 1.
Aperture Sight: Complete Marksman Challenge 2.
Telescopic Sight: Complete Marksman Challenge 3.
Gewehr 43: Reach level 7.
Suppressor: Complete Marksman Challenge 1.
Aperture Sight: Complete Marksman Challenge 2.
Telescopic Sight: Complete Marksman Challenge 3.
Rifle Grenade: Complete Marksman Challenge 4.
M1 Garand: Reach level 17.
STG-44: Reach level 37.
M1A1 Carbine Reach level 65.

Sub Machine Guns

Thompson: Reach level 4.
Suppressor: Complete Marksman Challenge 1.
Aperture Sight: Complete Marksman Challenge 2.
Round Drum: Complete Marksman Challenge 3.
MP40: Reach level 10
Suppressor: Complete Marksman Challenge 1.
Aperture Sight: Complete Marksman Challenge 2.
Dual Magazine: Complete Marksman Challenge 3.
Type 100: Reach level 25.
Ppsh: Reach level 41.

Shotguns

M1897 Trench Gun: Reach level 4.
Grip: Complete Marksman Challenge 1.
Bayonet: Complete Marksman Challenge 2.
Double Barreled Shotgun: Reach level 29.

Machine Guns

Type 99: Reach level 4.
Bipod: Complete Marksman Challenge 1.
Bayonet: Complete Marksman Challenge 2.
BAR: Reach level 4.
Bipod: Complete Marksman Challenge 1.
DP-28: Reach level 13.
MG 42: Reach level 33.
FG 42: Reach level 45.
Browning M1919: Reach level 61.

Pistols

Colt M1911: Reach level 4.
Nambu: Reach level 4.
Walther P38: Reach level 4.
Tokrev TT-33: Reach level 21.
.357 Magnum: Reach level 49.

Primary Grenades

Frag: Reach level 4.
N 74 ST: Reach level 4.
Molotov Cocktail: Reach level 10

Special Grenades

Smoke: Reach level 4.
Tabun Gas: Reach level 4.
Signal Flare: Reach level 4.