I have farmed hundreds of zombies, searched tens and tens of silver/yellow crates and despite finding every blueprint numerous times i still cannot find a research kit. all i need it for is to research 556 ammo then i am happy. are they still even in the game?
Yes, its RNG. I found several research kits in under 20~ zombie kills. keep trying!
Also black zombies or normal ones?
randomly generated number
random number generator
I found one in like, the first crate I raided