To put it simply, the bullet damage for both of these weapons increases as they get hotter. However, this only happens if you're playing as the Host, or if you're playing in Solo mode. If you're not the Host, the bullet damage of both weapons is locked at the lowest level, regardless of the heat gauge. This isn't too bad at lower difficulties, but at higher difficulties, with higher health enemies, it takes a lot longer to clear them.
As an example, at optimal range, my Tolchok does around 40-65 damage to regular enemies depending on the heat gauge, but it's locked to around 40 when I'm not the Host.
Likewise, my Tsiklon does about 20-40 damage to regular enemies, but it's locked to around the 20s when I'm not the Host.
Hopefully this will be fixed soon, both weapons have been bugged for months now.