Behind the neck military press
Target
Deltoid, Anterior
Synergists
Deltoid, Lateral
Supraspinatus
Triceps Brachii
Trapezius, Middle
Trapezius, Lower
Serratus Anterior, Inferior Digitations
Dynamic Stabilizers
Triceps, Long Head
Stabilizers
Trapezius, Upper
Levator Scapulae
VS
Regular military press
Target
Deltoid, Anterior
Synergists
Pectoralis Major, Clavicular
Triceps Brachii
Deltoid, Lateral
Trapezius, Middle
Trapezius, Lower
Serratus Anterior, Inferior Digitations
Dynamic Stabilizers
Triceps, Long Head
Biceps Brachii, Short Head
Stabilizers
Trapezius, Upper
Levator Scapulae
They're similar but not exact, but it's not worth ruining your shoulders. You might as well do regular military press. Plus reg.military helps you build a thick upper chest apparently. Few people are biomechanically designed to handle a behind the neck press. If something feels awkward and unatural I wouldn't bother doing it.