Open console in menu (default key: "~") and type command "promo DTN3RDM5" or other code from below:
-AZERTY keybord users, need to switch AZERTY to QWERTY keyboard layout

1. Codes are limited to region -> e.g. NA, EU, etc.
2. Most of the promo codes are limited for the first 10, 20 or 50 users when a new weapon model is released. Those are published on:
-reddit
-World of Guns steam news
-World of Guns facebook page
-Telegram channel (Russian https://t.me/wog_2018 )

Thanks for a bit o help and feedback to @observerbg

promo TTBE
1. ZIS - 3
2. HMMVVV A2
3. Daewoo USAS-12
4. RPD
5. S&W Model 500
6. Ruger Precision Rifle
7. M249 SAW
8. Walther MPL
9. PP-2000
10.M1941 Johnson rifle
11.Scorpion Evo 3 A1
12.SIG P210
13.Panzerschreck
14.HK 416
15.PM-63 RAK

@Arkendight, thanks for tip

promo ARMERO10
1. Beretta 92 FS
2. Uzi Full Auto
3. CZ-75
4. Glock 19
5. TAR-21
6. Brugger & Thomet MP9
7. Beretta PX4 Storm
8. HK MP5K PDW
9. HK MP7
10.Scorpion Evo 3 A1

@Firestorm, thanks for tip

This codes are limited to 5000+ users if any of them don't work, just write a comment with region.

Some of this codes are still working, its depends of country region:

promo DTN3RDM5 or promo C1YKYS6S
1. Maxim gun
2. COP .357 Derringer
3. Mauser 98K
4. Harpers Ferry
5. M14
6. Welrod
7. Ruger No.1
8. Winchester Model 21
9. M79
10. PTRD-41

promo XZCL or promo E202
1. Uzi Full Auto
2. Maxim gun
3. ZIS - 3
4. Ruger Super Redhawk
5. Browning Auto-5
6. PTRD-41
7. ArmaLite AR-18
8. HK MP7
9. PKM machine gun
10. Beretta 93R

promo 0M7K
1. PPD-40
2. Winchester Model 21
3. PTRD-41
4. Pancor Jackhammer
5. Owen Gun
6. Beretta 93R
7. FG 42
8. Madsen Machine Gun
9. FN F2000
10. M1941 Johnson rifle

promo N71F
1. Desert Eagle .44
2. Uzi Full Auto
3. S&W Model 53
4. Maxim gun
5. Nambu Type 14
6. Remington R51
7. Webley MK VI
8. Ruger Super Redhawk
9. RPD
10.Mars Automatic Pistol

promo ARMERO
1. Colt M1911A1
2. Desert Eagle .44
3. Beretta 92 FS
4. AK-47
5. Maxim gun
6. M16 A1
7. Glock 19
8. Barrett M107
9. Franchi SPAS 12
10.Ruger Super Redhawk
11.M79
12.Kriss Vector .45 ACP
13.Remington 700
14.HK G3 A3
15.Mars Automatic Pistol

Right now is almost impossible to get all/most of guns when u try to F2P (Free to play).
If you enjoy the game, u should consider buying Guns Full Access.
Just wait for -55% discount to get all guns and shooting ranges (22.49$, 13.49£, 20.69€ or 80.99 PLN)
Best way to get premium content (bikes, cars, military vehicles and skeletons) is to buy 500 Credits from shop (29.99$), all 14 things cost 400 Credits.