Can you use a 308 round in an ak-47?

Answer 1

7.62x39mm (Soviet M43) cartridge:

Case typeRimless, bottleneckBullet diameter7.92 mm (0.312 in)Neck diameter8.60 mm (0.339 in)Shoulder diameter10.07 mm (0.396 in)Base diameter11.35 mm (0.447 in)Rim diameter11.35 mm (0.447 in)Rim thickness1.50 mm (0.059 in)Case length38.70 mm (1.524 in)Overall length56.00 mm (2.205 in)Case capacity2.31 cm3 (35.6 gr H2O)Rifling twist240 mm (1 in 9.45 in)Primer typeBoxer Large RifleMaximum pressure355.00 MPa (51,488 psi)FillingSSNF 50 powderFilling weight18.21 gr

308 Winchester cartridge:

Case typeRimless, BottleneckBullet diameter0.308 in (7.8 mm)Neck diameter0.3433 in (8.72 mm)Shoulder diameter0.4539 in (11.53 mm)Base diameter0.4709 in (11.96 mm)Rim diameter0.4728 in (12.01 mm)Rim thickness0.0539 in (1.37 mm)Case length2.015 (51.18 mm)Overall length2.800 (71.12 mm)Case capacity56 gr H2O (3.6 cm3)Rifling twist1 in 12 in (305 mm)Primer typeLarge RifleMaximum pressure62,000 psi (430 MPa)

As you look at the two totally different cartridges, you'll see that there;s no way possible to use one in the other or vise versa.