As above, I've taken down numerous Jugs with Akimbo FMG9's.
Ive unloaded on Juggs with clips of AR's + Ext Mags, Strikers, USAS + Ext Mags and ive never been able to kill a Jugg as easily as I can with akimbo FMG's.
I usually flash them first and hit 'em with C4 if possible to make the task a bit easier.
Striker can kill one in 10 shots - for me that's about 2.5 to 3 seconds. I was amazed how quickly it does it - flash or stun it then spam that trigger.
Believe it or not I've taken a jug down alone with a mk14 extended mag. So if you are confident enough in your aim I'd suggest that.
Flash'em and the FMG akimbo'em
Armor piercing rounds (FMJ) can put them down pretty quick.