The Operational platoons are staffed with a platoon headquarters consisting of a Platoon Commander (usually a Captain), a platoon sergeant (usually a Staff Sergeant or Gunnery Sergeant), Platoon Radio Operator (normally a Staff Sergeant or Gunnery Sergeant), a Navy Special Amphibious Reconnaissance Corpsman, and a platoon Equipment NCO (Rigger/ Armorer).
There are three, six man teams in the platoon. Each Team consists of a Team Leader (SSgt), an Assistant Team Leader (SSgt/ Sgt), a Radio Operator, and three Reconnaissance Scouts.
The six-man team concept reflects real world experience. The Company formerly fielded 4 man teams but there were a number of issues that impacted negatively on the Marines. Consider that they must jump, dive, or walk in with all the gear necessary to complete the mission. The new surveillance and communications gear is lighter, stronger and more efficient than what it replaces, but there is more of it. Less then six cannot carry the equipment necessary for Deep Reconnaissance missions. Equally important is what the team does with a friendly casualty. Unless a 4-man team was willing to cache all of its equipment, they would not be able to carry a casualty out.
In Deep Reconnaissance, survival is based on stealth, and stealth is a by-product of alertness. A 4-man team does not have the numbers to provide an adequate rest cycle while maintaining proper security.
Though a Deep Reconnaissance mission requires that the team not be compromised, the reality of life is that they may. When that happens, the rules change. Because they are in the deep battle area, they cannot count on artillery support, and CAS and the extract birds may be a long time coming. They must be able to shoot, move and communicate, but unlike a Grunt, they are operating in a friendly vacuum. The 4 man team simply does not have enough guns to work as two elements.
The 6 man team also provides the numbers necessary to perform a Direct Action mission. Remember that these missions will take place in a non-permissive (or at best, a semi-permissive) environment. The smaller teams are just an invitation for failed missions and higher casualties.
On the other side of the coin, increasing the team drastically increases the chance of detection. More than 6 and the patrol becomes too unwieldy for clandestine operations.
6 man teams are a compromise, and it is the best available solution.
For Direct Action missions, the platoon is configured into a single unit, and task organized with Explosive Ordnance Disposal (EOD) technicians, a Reconnaissance and Surveillance (R&S) section (drawn from the BLT Scout/ Sniper Platoon), and a Security Element (also drawn from the BLT) as well as other mission related personnel.