zincwarrior: Check out the following website where they explore bullet penetration quite extensively concentrating on wall penetration results.
http://www.theboxotruth.com/
--> edit to add the interior link to penetration tests
http://www.theboxotruth.com/docs/theboxotruth.htm
They have a lot of testing posted and their presentation is often entertaining. You'd be surprised at how far buckshot penetrates.
The key take-away is bullet selection, not just caliber. Though you won't find much on the 5.45x39 V-Max, it is essentially a sized down .223/5.56 V-Max and you can expect similar results, although the 5.45x39 velocity is not as fast as .223/5.56 from the muzzle.
Responding to the OP: I'm counting on my AK74 with 5.45x39 V-Max as my family self defense carbine. It is equipped for night-time use (sight/light/flash hider) and is stored in a biometric rifle safe for easy access. I also have a pistol with night sights and a TLR-4 light & laser in a biometric pistol safe. My quick access rifle safe also has a 20 gauge loaded with #4 buck - the wife prefers that to the AK74
.