I think I found this image on Reddit when I still used that horrid site. I believe it was in a post where someone was showing off their Metro-inspired airsoft RPK.

I should change the banner image at some point, but I don’t know what would fit best

It’s variant of RPK, light machine gun developed to be the partner to AKM - improved AK-47. They were produced in the millions and the numbers of variants and derivatives made around the world is simply astounding. The gun is still in wide usage and new variants are even still being developed.