I personally have never been a fan of Stalker. I don't fell at advantage at all using that perk. My go to FAD setup when I got it gold:
FAD grip extended mags
With extended mags you get 63 rounds. You probably won't have to reload throughout your whole life and if you do you need to reevaluate how you're using it. I typically get a kill at all ranges with a four round burst with this setup. Learn your weapon and how long to hold the trigger down. Learn how to shoot it in four round bursts.
The Fad has really quick handling and nice iron sights. A fairly quick rate of fire but the shots seem to group nicely.
Try this class the FAD with Suppressor and Grip with the M9A1 as your secondary with Extended Mags your Lethal is a Semtex or C4 and your Tactical is a Stun or Flash Bang your perks will be Stalker, Dead Silence, Sleigh of Hand and Ready Up. This class needs a Specialist Package your perks for this. One will be Quickdraw then Amplify and then Scavenger as your third perk as for the perks you get when you get your bonus it should be Dead Eye and Off The Grid.
Alright, thanks to everyone who offered. It seems the consensus is extended clip + foregrip. I didn't need extended clip because I carry a pistol and use it. So, if my primary runs dry I just pull it and keep fighting. However, I did try out the grip and that made a huge different. I ended up with this.
Attachments: Grip, VRM sight, Suppressor
Attachments: Dual Weild, Supressor
Perks: Stalker, Focus, Steady Aim, Extra Attachment
I ended up using the grip and the FAD worked well at both close and long range. I don't sprint with this build so, ready up wasn't necessary and I have the dual silenced pistols to fall back to. Thanks to everyone who contributed.