I'm using;
Muzzle break, foregrip, red dot.
With rapid fire, maneuverability and aim enhance.
I'm not sure if its my imagination but the last couple of days I'm suddenly finding the grendel easier to use and I am taking out scar users somehow. Normally for this kinds of things I wouldn't ask, but Cry-devs do have a habit of introducing some tweaks and seeing if people notice or whether the vets are just full of BS.
Vet: X is still broken and doesn't work!!!
Cry-Dev: We fixed this ages ago and you didn't notice, u mad?
Generally I do get quite a laugh out it, but I am not sure if its my imagination this time. My stats don't look any better so I am guess it could also just be my imagination.