HD,
I found one more picture..
The Trooper passing the Carbine carry case up in to the plane is the type I have with the rigger added extension sewn on it. See the case like yours in front, it has a 2 -15rd mag pouch attached up at the fold. Looking closely the case like yours sure looks like it is 'Strapped' just above the knee of the Trooper.



Charlie-Painter777