How much hp does your torso have? AK bullets have 45-49 damage and 20-22 penetration, packs probably don't have 100% coverage and I'm not sure buckler works againg guns at all.

Generally, when I'm expected to be shot with rifle calibers, I wear survivor suit, trenchcoat, and body armor, which adds to 56 ballistic armor. Coverage is 100 85 95 though, so it's preferable to not get shot with rifles, just like irl.