Well I see that some folks dont agree with my points as to why AK carry is a bad idea.
I have an SAR-1 with a sling myself and I am not against using one for self defense, but it would be in a SHTF situation or in a riot where I am defending a fixed location or if I had to go out on patrol to get milk for the kids, or I knew or suspected that the bad guys would be carring heavy hardware. In these situations I want it visible on a sling for fast access.
For normal everyday carry the idea is self defense, and concealment. I like the tactical advantage of having a weapon concealed, but easy to access in an inconspicuous manner. An AK in a guitar case has serious tactical disadvantages for a normal CCW situation.
Heres how I see a typical defense situation Walking down the street and two muggers approach, I stick my hand in my pocket and draw a gun bang bang, muggers down, they never saw it coming. Or they take me unawares and say give me you wallet I put hand in pocket to comply and come up with a firing 9mm Surprise.!!!!
Your friend, places guitar case on ground undoes all four latches raises lid, hmmmmmm, the mugger see and relieve him of the AK, or they knock him to the ground and take his guitar so they can sell it for crack.
To quickly access it in a surprise situation he would need to carry it slung, so then the muggers leave him alone, but lets face it in most cities in the US he would find himself facing the SWAT team cause it would alarm the sheeple.
Thats reality.
As far as accuracy and safety, folks here are always saying that overpenetration is a huge problem, with PISTOL bullets. The AK round is fmj (even the soft and hollow points dont expand often) and 2400 fps, if he makes a hit on his first shot and fires no more, the bullet will go through the perp and be traveling fast enough to kill a child or an old lady 50 yards away.