HEAT INDEX
 
75
80
85
90
95
100
105
110
115
20
72
77
82
87
93
99
105
112
120
30
73
78
84
90
96
104
113
123
135
40
74
79
86
93
101
110
123
137
151
50
75
81
88
96
107
120
135
150
 
60
76
82
90
100
114
132
149
 
 
70
77
84
93
106
124
144
 
 
 
80
78
86
97
113
136
 
 
 
 
90
79
88
102
122
 
 
 
 
 
100
80
90
108
 
          

 
 
This heat index table shows only part of the picture for those of us who served in Vietnam. Depending on your MOS (Military Occupational Specialty), you may carry a several pound flack jacket, a couple hundred rounds of ammunition, a rifle, several grenades. Then enough food for one to three days and water, and of course a helmet that feels like it weighs a hundred pounds.

Additional equipment would be a belt or two of machine gun ammo for the gun team or perhaps a couple or three 60 mm motor shells. In my case and many we carried a 35 pound PRC-25 radio also.  Claymore mines was a favorite for most grunts. You may also find a book or Bible in ones pouch and some C-4 to cook with. (Yes, I know, C-4 is plastic explosives, but man can it cook).

So as you see, the above heat index means little to a man carrying 70 to 90 pounds on his back.