Will a .308 Winchester Penetrate Drywall (Gypsum)?
Yes — defeats a 13 mm drywall (gypsum) barrier
Penetration depth
457 mm (18.0″)
Impact velocity
840 m/s (2756 fps)
Muzzle energy
3352 J (2472 ft-lb)
Bullet behaviour
Intact
Fired at the muzzle, a representative .308 Winchester load (9.5 g, FMJ, 840 m/s) reaches roughly 457 mm (18.0 inches) into drywall (gypsum). That is enough to defeat a typical barrier of this material — treat anything behind it as exposed.
About Drywall (Gypsum)
One sheet of interior drywall is ~13 mm; a wall is two sheets and a gap.