Ballistic limit

The ballistic limit or limit velocity is the velocity required for a particular projectile to reliably (at least 50% of the time) penetrate a particular piece of material. In other words, a given projectile will generally not pierce a given target when the projectile velocity is lower than the ballistic limit. The term ballistic limit is used specifically in the context of armor; limit velocity is used in other contexts.

The ballistic limit equation for laminates, as derived by Reid and Wen is as follows:

V b = π Γ ρ t σ e D 2 T 4 m [ 1 + 1 + 8 m π Γ 2 ρ t D 2 T ]
where

Additionally, the ballistic limit for small-caliber into homogeneous armor by TM5-855-1 is:

V 1 = 19.72 [ 7800 d 3 [ ( e h d ) sec ⁡ θ ] 1.6 W T ] 0.5
where