Ranger Ranks and Weapons

The backbone of the Ranger Battalion is the Private with his rifle. While higher ranks may take other weapons (if they have the marksmanship badge for it), Privates are restricted to the Garand with Grenades, unless specifically authorized by the officer in charge. All members are expected to be in uniform at all times, including the proper tag and uniform of the day. Members of forums are expected to use their proper helmet marking icon as their avatar.
Advancement in the Rangers reflects the unit's elite status, in that it is difficult and time consuming. The benefit is, when you acheive a rank, you and everyone else knows you've EARNED it. Note that everyone can reach the rank of Private First Class (PFC), but the Non Commissioned Officer (NCO) and Officer ranks are limited, even if you meet the requirements, you may have to wait for a slot to open up to be promoted.

RankIconTag formatAuthorized Weapons and Promotion Criteria
Recruit
(Boot)
recruit[5R]rM1 Garand and Grenades only.

From recruit to Private To advance from recruit to Private requires excellent individual infantry skills. This is tested in the following way:
A server is set up, "day castle" map, firefight mission, German Heer veteran enemies, 15 minute time limit. The recruit may only use the M1 Garand rifle and 4 grenades. He must then clear the map of all enemies, within the time limit, solo. Two respawns are allowed. An officer must be present, but may not help the recruit in any way. One attempt per day is allowed. Every attempt must be scheduled beforehand. An alternate test allowed are two privates taking the test together, with one respawn each. If either one dies without a respawn left, both fail.

PrivatePrivate[5R]PvtM1 Garand and Grenades only.

From Private to Private First Class (PFC) Before a Private may attempt to advance to PFC, he must have achieved both a Rifle marksmanship badge and a Combat Infantry badge. If these requirements are met, he then has to wait for another Private who meets these same requirements to be ready to test alongside him. The test:
A server is set up, mission 4 "Black needle", German Heer veteran enemies, 20 minute time limit. One Private armed with Garand and Bazooka, one with Garand and grenades. They must work together, as a team, complete the mission, with two respawns, if either of them is killed without respawn, the test is failed for both. An officer must be present, but may not help the Privates in any way. One attempt per day is allowed.

Private
First Class
Private first class[5R]PFCM1 Garand and Grenades, may be assigned to carry the platoon machine gun or bazooka by officer or senior NCO.

From PFC to Corporal 15 Battle points, the Rifle and Carbine marksmanship badges.

CorporalCorporal[5R]CplAny small arm*, may be assigned the platoon machine gun, bazooka, or sniper rifle by officer or senior NCO.

From Corporal to Sergeant 30 Battle points, the previous marksmanship badges, and the Auto Rifle (BAR) marksmanship badge.

SergeantSergeant[5R]SgtPlatoon machine gun, bazooka, or sniper rifle, unless detailed, then any small arm.

From Sergeant to 1st Sergeant 45 Battle points, the second combat infantry badge, the previous marksmanship badges, and the Machine gun marksmanship badge.

1st Sergeant1st Sergeant[5R]1StPlatoon machine gun, bazooka, or sniper rifle, unless detailed, then any small arm.

From 1st Sergeant to 2nd Leutenant 60 Battle points, the second combat infantry badge, the previous marksmanship badges, and the Rocket Launcher (Bazooka) marksmanship badge.

2nd Leutenant2nd Leutenant[5R]2ltAny.

From 2nd Leutenant to 1st Leutenant 100 Battle points, the second combat infantry badge, the previous marksmanship badges, and the Submachine gun marksmanship badge.

1st Leutenant1st Leutenant[5R]1ltAny.

From 1st Leutenant to Captain 140 Battle points, the third combat infantry badge, the previous marksmanship badges, and the Sniper marksmanship badge.

CaptainCaptain[5R]CapAny.

From Captain to Major 180 Battle points, the third combat infantry badge, the previous marksmanship badges, and the Pistol marksmanship badge.

MajorMajor[5R]MajAny.

From Major to Lt. Colonel 220 Battle points, the third combat infantry badge, the previous marksmanship badges, and the Bayonet marksmanship badge.

Lt. ColonelLeutenant Colonel[5R]ColAny

Note: All ranks are required to use the Ranger skin at all times, unless authorized by the officer in charge to change.

* Small arms are M1 Garand, M1 Carbine, M1a1 submachine gun, M3a1 submachine gun. Check here for weapon descriptions. Note that regardless of rank, a Ranger may only take a weapon into battle for which they've earned a marksmanship badge.

The images are taken from Ranger helmet markings:
helmet markings
No stripe means an enlisted man, a horizonal stripe means an NCO, and a vertical stripe means an officer. The photo identifies an officer of the 2nd Ranger Battalion.