5.56 vs 7.62 � Lethality & Survivability

Lethality vs. Survivability: 5.56�45mm NATO vs. 7.62�51mm NATO (0.308)

Quick Data Table

Attribute	5.56�45mm (5.56-NATO)	7.62�51mm (.308-NATO)
Typical cartridge	M855/SS109 (62�gr, ~2.9�g)	M80/AP (147�gr, ~9.5�g)
Muzzle velocity	~950�970�m/s (3,100�3,200�ft/s)	~830�850�m/s (2,700�2,800�ft/s)
Kinetic energy @ 300�m	~1,400�J (�1.4�kJ)	~1,600�J (�1.6�kJ)
Penetration in gelatin (30�mm)	50�55�mm (hollow-point/AP)	70�80�mm (AP)
Wound channel	Smaller (~12�15�mm), deep but less tissue damage	Larger (~20�25�mm), more cavitation
Prob. of immediate incapacitation	~55-65�% (head/neck/center mass @ =200�m)	~70-80�%
Risk to by-standers (secondary fragmentation)	Lower	Higher

What �Lethality� Actually Means

Immediate Kill Probability: 5.56 has high velocity & flat trajectory�good for quick stops at 200�300�m, but its lighter projectile may fragment or miss vital organs unless hit precisely. 7.62�s heavier mass + larger diameter gives a higher chance of striking a vital organ or causing catastrophic damage even with slightly off-target shots.
Wound Severity: 5.56 produces a narrow but deep channel; bullet fragments can create multiple secondary wounds, yet overall tissue destruction is less than a .308 round. 7.62 creates a wide, high-energy cavity that disrupts multiple organs and structures.
Penetration & Over-penetration: 5.56 is less likely to penetrate hard targets or exit fully through a body�lower risk of secondary injury. 7.62 can pass through walls, armor, or even the human body, posing danger to others behind the target.

Survivability Factors

Medical Treatment Needed: 5.56 often requires field evacuation + surgery for fractures/internal bleeding; less catastrophic damage may allow faster stabilization. 7.62�s severe injuries (e.g., organ rupture, massive blood loss) usually require immediate surgical intervention�often impossible in the field.
Time to Death: 5.56: If critical organs are not hit, a wounded soldier might live hours/days before death�allowing extraction. 7.62: If vital structures are struck, death can occur within minutes.
Likelihood of Rescue Success: 5.56: Higher if bullet misses major organ or causes less internal damage; field medics may stabilize the casualty for transport. 7.62: Lower due to higher risk of rapid deterioration and difficulty providing adequate care in combat conditions.

Scenario: �Taking Two People Off the Battlefield�

5.56 Hit but Not Kill: Soldier is wounded (non-fatal internal injury or broken bone). Requires medical extraction (often medevac). While alive, can be removed from combat ? two �people off the battlefield� (one killed + one rescued).
7.62 Immediate Kill: One enemy eliminated instantly � no extraction needed. Heavier bullet may also cause secondary injuries or over-penetrate into friendly positions.

Bottom Line Summary

Lethality (instant kill rate): 7.62 higher ? wider wound cavity, more likely to hit vital organs.
Survivability if Hit but Not Killed: 5.56 better � lower tissue destruction, easier field medical care.
Collateral Damage / Over-penetration Risk: 5.56 lower; 7.62 higher.
Logistics & Weight (capacity): 5.56 lighter, higher capacity ? fewer resupply trips; 7.62 heavier, lower capacity.

Take-away

Lethality: 7.62 wins because of mass, larger wound cavity, and higher probability of incapacitation.
Survivability (if the casualty survives the initial hit): 5.56 wins due to less catastrophic damage and more manageable field care.

Ultimately, choose the round that matches your tactical priorities: instant kill vs. minimizing friendly casualties while still neutralizing the enemy.