I was slightly unsure about the whole questionable kills thing so I only included the kills that I knew I had got with assault rifles. Which left out some of the times I got one or two kills with PDW's..?
Total : 28/350
Good start man
Yes the kills only count if it is either your best weapon or a ribbon.
I always suggest the easiest way to get this is to ask someone to play DOM with you so you can concentrate on infantry kills, all with one gun.
CAG Dogg Level: 47 [?]
Experience: 6,258,999
Next Level: 7,172,237