Here is the list of all the rank unlockables, for anyone who wants to know.

Private:

- All starting equipment

- Demolitions Class Weapon Class

- Sniper Class Weapon Class

Lance Corporal:

- Create a Class

- Gun Challenges

- New playlists

Corporal:

- M40 Sniper Rifle

- Last Stand Perk Class 3

- Boot Camp Challenges 1

Sergeant:

- M4 Carbine Assault Rifle

- UAV Jammer Perk Class 2

- Clan Tag

Staff Sergeant:

- Mini Uzi Submachine Gun

- Bomb Squad Perk Class 1

- Boot Camp Challenges 2

Gunnery Sergeant:

- M1911 Pistol

- Martyrdom Perk Class 2

- Boot Camp Challenges 3

Master Sergeant:

- M60E4 Light Machine Gun

- Sleight of Hand Perk Class 2

- Operations Challenges

Master Gunnery Sergeant:

- Dragunov Sniper Rifle

- Claymore Perk Class 1

- Operations Challenges 2

2nd Lieutenant:

- G3 Assault Rifle

- Iron Lungs Perk Class 3

- Operations Challenges 3

1st Lieutenant:

- AK-74U Submachine Gun

- Double Tab Perk Class 2

- Killer Challenges

Captain:

- M1014 Shotgun

- Bandolier Perk Class 1

- Killer Challenges 2

Major:

- R700 Sniper Rifle

- Eavesdrop Perk Class 3

- Killer Challenges 3

Lieutenant Colonel:

- G36C Assault Rifle

- Overkill Perk Class 2

- Killer Challenges 4

Colonel:

- P90 Submachine Gun

- Frag x 3 Perk Class 1

- Humiliation Challenges

Brigadier General:

- Desert Eagle Pistol

- Dead Silence Perk Class 3

- Humiliation Challenges 2

Major General:

- M14 Assault Rifle

- Humiliation Challenges 3

- Humiliation Challenges 4

Lieutenant General:

- Barret Sniper Rifle

- Humiliation Challenges 5

- Elite Challenges

General:

- MP44 Assault Rifle

- Elite Challenges 2

- Elite Challenges 3

- Commander Prestige Mode

- Golden Desert Eagle

Below is a chart of XP needed for each rank.