First Blood Genocide glitch

[Riff]

So I've recently finished hard mode and the only achievement left for me to do is genocide. But for the life of me I can't replicate the bug where the games puts a spawn after you kill a few guys. I'm able to do it but only with one or two kills, which isn't too efficient while my friend was able to get up to 4 and die very quickly. Are there some specific things I'm missing in this?

[The Shark Shaman]

Within the first two seconds of first blood loading is where your level checkpoint gets placed, so within those two seconds: grab the gun and blast 3-6 mobsters then die to one, the checkpoint should register your death and allow infinite reset kills. Spam for like 45 minutes and bingo, GENOCIDE done