Of the 51 weapons available in Modern Warfare 3 at launch, 28 are earned by increasing your player level, and the others are instead acquired through Platforms by increasing weapon levels.
| # | Requirement | Weapon and Platfom unlocks |
|---|---|---|
| 1 | Player Level 4 | M4 Assault Rifle M4 Platform |
| 2 | Player Level 4 | MP7 (VEL 46) SMG LMP Platform |
| 3 | Player Level 4 | Bryson 800 Shotgun Bryson 800 Series Platform |
| 4 | Player Level 4 | Sakin MG LMG Sakin MG Platform |
| 5 | Player Level 4 | EBR-14 Marksman Rifle Ordnance Weapon Platform |
| 6 | Player Level 4 | MCPR-300 Sniper Rifle MRBA Platform |
| 7 | Player Level 4 | P890 Handgun Bruen 890 Platform |
| 8 | Player Level 4 | PILA Launcher No Platform |
| 9 | Player Level 5 | PDSW 528 SMG Tactique Defense Platform |
| 10 | Player Level 7 | SP-R 208 Marksman Rifle Bryson Long Rifle Platform |
| 11 | Player Level 9 | Expedite 12 Shotgun Expedite Platform |
| 12 | Player Level 13 | .50 GS Handgun Sakin G Series Platform |
| 13 | Player Level 14 | STRELA-P Launcher No Platform |
| 14 | Player Level 16 | Lachmann-762 Battle Rifle Lachmann and Meer Platform |
| 15 | Player Level 17 | Combat Knife Secondary Melee No Platform |
| 16 | Player Level 19 | TAQ-56 Assault Rifle Tactique Verte Platform |
| 17 | Player Level 23 | Kastov 762 Assault Rifle Kastovia Platform |
| 18 | Player Level 24 | JOKR Launcher No Platform |
| 19 | Player Level 25 | RAAL MG LMG RAAL Platform |
| 20 | Player Level 28 | Lockwood MK2 Marksman Rifle Mark 2 Platform |
| 21 | Player Level 31 | X12 Handgun XRK Platform |
| 22 | Player Level 32 | RPG-7 Launcher No Platform |
| 23 | Player Level 36 | Lockwood 300 Shotgun Lockwood Sport Platform |
| 24 | Player Level 37 | Riot Shield Primary Melee No Platform |
| 25 | Player Level 38 | Fennec 45 SMG Fennec Platform |
| 26 | Player Level 39 | Basilisk Handgun Basilisk 500 Platform |
| 27 | Player Level 41 | STB 556 Assault Rifle Bruen Bullpup Platform |
| 28 | Player Level 44 | Signal 50 Sniper Rifle Signal Platform |
Note: For the weapon unlocks listed with a level 4 requirement, they’re first available to use and equip when custom loadouts are unlocked.
As mentioned, many other weapons are unlocked by levelling weapons within Platforms.
Below is a list of all the weapons unlocked by increasing the level of weapons within the Platforms mentioned above:
| # | Weapon | Weapon Level Requirement |
|---|---|---|
| 1 | FTAC Recon Battle Rifle | M4 at level 13 |
| 2 | 556 Icarus LMG | M4 at level 18 |
| 3 | M16 Assault Rifle | 556 Icarus at level 13 |
| 4 | FSS Hurricane SMG | FTAC Recon at level 16 |
| 5 | Bryson 890 Shotgun | Bryson 800 at Level 16 |
| 6 | S0-14 Battle Rifle | EBR-14 at Level 12 |
| 7 | SA-B 50 Marksman Rifle | SP-R 208 at Level 13 |
| 8 | LA-B 330 Sniper Rifle | SA-B 50 at Level 16 |
| 9 | SP-X 80 Sniper Rifle | LA-B 330 at Level 17 |
| 10 | Lachmann-556 Assault Rifle | Lachmann-762 at level 13 |
| 11 | LM-S Marksman Rifle | Lachmann-762 at level 16 |
| 12 | Lachmann Sub Submachine Gun | Lachmann-556 at level 12 |
| 13 | RAPP H Light Machine Gun | Lachmann-556 at level 16 |
| 14 | TAQ-V Battle Rifle | TAQ-56 at Level 11 |
| 15 | TAQ-M Marksman Rifle | TAQ-56 at Level 20 |
| 16 | Kastov-545 Assault Rifle | Kastov-762 at Level 10 |
| 17 | RPK LMG | Kastov-762 at Level 16 |
| 18 | Kastov-74U Assault Rifle | Kastov-545 at Level 13 |
| 19 | Vaznev-9K SMG | Kastov-74U at Level 15 |
| 20 | Minibak SMG | Vaznev-9K at Level 14 |
| 21 | X13 Auto Handgun | X12 at Level 10 |
| 22 | MX9 SMG | STB 556 at level 13 |
| 23 | HCR 56 LMG | STB-556 at level 20 |
Note: Some Platforms don’t have any weapon unlocks currently and as such, are comprised of just a single weapon.
These can still be levelled with their own attachments to unlock, but they do not unlock any additional weapons. They are as follows: