Body armor is graded based on the type of bullet that it is intended to withstand.
Factors impacting penetrating power of a bullet:
(1) kinetic energy
(2) type of bullet (jacketed, hollow point, armor piercing, etc)
kinetic energy of a bullet in kg•m^2 per sec^2 =
= 0.5 * (bullet weight in grams) / 1000 * ((velocity in meters per second)^2)
|
Armor Type |
Gun |
Grams |
Type |
meters per second |
kinetic energy |
|
I |
0.22 LR |
2.6 |
LRN |
320 |
133 |
|
I |
0.380 ACP |
6.2 |
FMJ RN |
312 |
301 |
|
IIA |
9 mm |
8.0 |
FMJ RN |
332 |
441 |
|
IIA |
0.40 S&W |
11.7 |
FMJ |
312 |
569 |
|
II |
9 mm |
8.0 |
FMJ RN |
358 |
513 |
|
II |
0.357 Mag |
10.2 |
JSP |
427 |
930 |
|
IIIA |
9 mm |
8.0 |
FMJ RN |
427 |
729 |
|
IIIA |
0.44 Mag |
15.6 |
SJHP |
427 |
1,422 |
|
III (rifle) |
7.62 mm NATO |
9.6 |
FMJ |
838 |
3,370 |
|
IV |
0.30 cal |
10.8 |
FMJ AP |
869 |
4,077 |
where:
• LR = long rifle, LRN = lead round nose, ACP = , S&W = Smith & Wesson; Mag = magnum, ACP = automatic Colt pistol
• FMJ = full metal jacket, RN = round nose, JHP = jacketed hollow point, AP = armor piercing, SJHP = semi-jacketed hollow point; JSP = jacketed soft point
