Depends heavily on the time frame: Pre 105 PA and Post 105 PA (the introduction of the new weapons, armor, vehicles, and robots).
And I assume you mean a standard rifle/infantry squad: Sourcebook One gives us our best look at a standard 8 man infantry squad (Short Range Reconnaissance Squad):
Pre 104
4 Light infantry soldiers (Grunts): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades.
2 Heavy infantry soldiers (Grunts): CA-1 heavy body armor, armed with C-14 Fire Breather assault rifle or C-27 plasma cannon, two fragmentation hand grenades. Plus the two-man
team operates a CR-1 Rocket launcher (one soldier carries 2D4 mini-missiles, the other carries the CR-1).
1 Military specialist (espionage training and squad leader): CA-2 body armor, vibro-blade of choice, CV-212 variable laser rifle or C-12 heavy laser rifle, C-18 laser pistol, S.D.C. automatic weapon of choice, and three plasma grenades. May wear SAMAS power armor or jet pack (40% chance).
1 Technical officer (communications): Long range radio, radar, and portable computer. Same arms and armor as light infantry.
Note: Travel on foot; no vehicle. Stealth and defensive maneuvers are required. Thus two to four Dog Pack soldiers may be substituted for two light or heavy infantry soldiers.
Post 105 PA
4 Light infantry soldiers (Grunts): CA-4 Dead Boy body armor, CP-40 pulse laser rifle, C-20 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades.
2 Heavy infantry soldiers (Grunts): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades. Plus the two-man team operates a CR-1 Rocket launcher (one soldier carries 2D4 mini-missiles, the other carries the CR-1).
1 Military specialist (espionage training and squad leader): CA-6EX body armor, vibro-blade of choice, CV-212 variable laser rifle or CP-50 "Dragonfire" assault rifle, CP-30 laser pistol, S.D.C. automatic weapon of choice, and three plasma grenades. May wear Terror Trooper or "Smiling Jack" SAMAS power armor or jet pack (40% chance). If so, they will be armed with the heavier CTT-M20 missile rifle or CTT-P40 rifle instead of the CV-212 or Dragonfire.
1 Technical officer (communications): Long range radio, radar, and portable computer. Same arms and armor as light infantry.
Note: Travel on foot; no vehicle. Stealth and defensive maneuvers are required. Thus two to four Dog Pack soldiers may be substituted for two light or heavy infantry soldiers.
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Now all of that said, there are more than a few of us who disagree with the 8 man squad concept, but it is canon. Were I to base it off of the 9 man squad (the US Army ideal) then it would go like this: A 13 man squad (the marine model) would simply add a third fireteam.
Pre 104
--Squad Leader (Pre-105 PA):
Heavy infantry soldier (Grunt NCO): CA-1 heavy body armor, armed with C-14 Fire Breather assault rifle or C-27 plasma cannon, two fragmentation hand grenades. May wear SAMAS power armor or jet pack (40% chance).
--Fireteam Alpha
-Team Leader: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades.
-Heavy Weapons Gunner: Heavy infantry soldier (Grunts): CA-1 heavy body armor, armed with C-27 plasma cannon, two fragmentation hand grenades. Plus carries a CR-1 Rocket launcher. The Rifleman carries the mini-missile ammunition.
-Grenadier: Heavy infantry soldier (Grunt): CA-1 heavy body armor, armed with C-14 Fire Breather assault rifle or C-27 plasma cannon, two fragmentation hand grenades.
-Rifleman: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades. Also carries 6 Mini-missiles in a backpack for the CR-1.
--Fireteam Bravo
-Team Leader: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades.
-Heavy Weapons Gunner: Heavy infantry soldier (Grunt): CA-1 heavy body armor, armed with C-27 plasma cannon, two fragmentation hand grenades. Plus carries a CR-1 Rocket launcher. The Rifleman carries the mini-missile ammunition.
-Grenadier: Heavy infantry soldier (Grunt): CA-1 heavy body armor, armed with C-14 Fire Breather assault rifle or C-27 plasma cannon, two fragmentation hand grenades.
-Rifleman: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades. Also carries 6 Mini-missiles in a backpack for the CR-1.
Post 105 PA
--Squad Leader (Post 105 PA): Heavy infantry soldier (Grunt): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades. May wear Terror Trooper or "Smiling Jack" SAMAS power armor or jet pack (40% chance). If so, they will be armed with the heavier CTT-M20 missile rifle or CTT-P40 rifle instead of the CV-212 or Dragonfire.
--Fireteam Alpha
-Team Leader: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades. Will also carry a higher quality field radio, possibly a light backpack unit.
-Heavy Weapons Gunner: Heavy infantry soldier (Grunt): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades. Plus carries a CR-1 Rocket launcher. The Rifleman carries the mini-missile ammunition.
-Grenadier: Heavy infantry soldier (Grunt): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades.
-Rifleman: Light infantry soldier (Grunt): CA-4 Dead Boy body armor, CP-40 pulse laser rifle, C-20 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades. Also carries 6 Mini-missiles in a backpack for the CR-1.
--Fireteam Bravo
-Team Leader: Light infantry soldier (Grunt): CA-2 Dead Boy body armor, C-12 laser rifle, C-18 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades. Will also carry a higher quality field radio, possibly a light backpack unit.
-Heavy Weapons Gunner: Heavy infantry soldier (Grunt): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades. Plus carries a CR-1 Rocket launcher. The Rifleman carries the mini-missile ammunition.
-Grenadier: Heavy infantry soldier (Grunt): CA-4 heavy body armor, armed with CP-50 "Dragonfire" assault rifle or C-29 "Hellfire" plasma cannon, two fragmentation hand grenades.
-Rifleman: Light infantry soldier (Grunt): CA-4 Dead Boy body armor, CP-40 pulse laser rifle, C-20 laser pistol, S.D.C. submachinegun, vibro-knife, and two fragmentation hand grenades.. Also carries 6 Mini-missiles in a backpack for the CR-1.
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Now I will say that a lot of the 9 man and 13 man squad is based on my rewrite of the CS OCCs, which is MOS based, not solely OCC based.