Human Factors ProblemsHuman Factors Problems

And the Design of the And the Design of the M-16 RifleM-16 Rifle

History of the M-16History of the M-16

First introduced in the First introduced in the Vietnam WarVietnam WarInitial design had Initial design had many flawsmany flaws– JammedJammed– MisfiredMisfired– UnreliableUnreliable

““The weapon has failed us at crucial The weapon has failed us at crucial moments when we needed fire power moments when we needed fire power most. In each case, it left Marines naked most. In each case, it left Marines naked against their enemy. Often, and this is no against their enemy. Often, and this is no exaggeration, we take counts after each exaggeration, we take counts after each fight, as many as 50% of the rifles fail to fight, as many as 50% of the rifles fail to work.”work.”

Major Design ProblemsMajor Design Problems

Cyclic RateCyclic Rate

Trigger & FireTrigger & Fire

ControlControl

HandguardHandguard

Mag CapacityMag Capacity

Target SightingTarget Sighting

Cyclic RateCyclic Rate

Too highToo high– Resonant Mechanisms Resonant Mechanisms

designed for certain designed for certain number of roundsnumber of rounds

MisusedMisused– JammedJammed– Increased workloadIncreased workload

Hydraulic Buffers Hydraulic Buffers

Trigger & FireTrigger & Fire

Semi-automatic & Full-automatic Fire Semi-automatic & Full-automatic Fire ModesModes

Selector Switch on side of gunSelector Switch on side of gun– Inconvenient Inconvenient – Loss of valuable time in battleLoss of valuable time in battle

Trigger & Fire Trigger & Fire (continued)(continued)

TAC triggerTAC trigger– No release of trigger necessaryNo release of trigger necessary– In action, can be the difference between life In action, can be the difference between life

and deathand death

ControlControl

M16 kickbackM16 kickback– Up and to the rightUp and to the right– InaccuracyInaccuracy

Dangerous in training and on battle fieldDangerous in training and on battle field

Muzzle BrakeMuzzle Brake

HandguardHandguard

MaintenanceMaintenance– Locks difficult to removeLocks difficult to remove

Possible design changePossible design change– Pressurized lockPressurized lock– However, unrealistic without complete However, unrealistic without complete

redesignredesign

Mag CapacityMag Capacity

Largest ammunition magazine holds only Largest ammunition magazine holds only 30 rounds30 rounds– In full auto mode, rounds quickly depletedIn full auto mode, rounds quickly depleted

Advantageous to double magazine Advantageous to double magazine capacitycapacity– Less time spent on reloadingLess time spent on reloading

Mag Capacity Mag Capacity (continued)(continued)

Possible Redesign of Possible Redesign of MagazineMagazine

– Clip holding 60-70 Clip holding 60-70 roundsrounds

– Circular or box shaped Circular or box shaped magazine instead of magazine instead of linearlinear

Target SightingTarget Sighting

Sighting AccuracySighting Accuracy

– Difficult to aimDifficult to aim