I've been trying for ages!
My highest kill streak I ever got was 19, by running around with an 1887 (FMJ). But that was just luck.
Now I've tried sniping as according to my mate thats the easiest way, BUT NO STILL NO NUKE! :@
The three kill streaks I have are Hairiers, chopper gunner and Nuke.
But I seem to keep getting spotted in my ghillie, withe Cold-blooded pro and ninja pro. GRRR.