I think its more an archetype problem myself. Both weapons got put into high ttk archetypes. Red Death I could see the complaint since it also heals on kill and gets a damage boost when its already in an 2 bursts to kill archetype, as well as having absurd range which I see as an issue with another PvP popular exotic being Conditional Finality having absurd handling as well as the fact of a unique firing pattern similar to Acrius where its a hitscan deadzone, so it doesn't matter how many "pellets" hit as long as your in a certain deadzone it treats it as all pellets hitting at full damage. Khvostov? Nah thats just showing how overtuned 600 RPM autos have been for a long time now thanks to the Summoner meta. Khvostov only has the advantage of being a weapon thats easy to punish clumping up with