For example, an unmodded Snipetron has 100 base damage. With a rank 3 Charged Chamber you would have: 100 * (1 + 0.4) = 140 total damage on the first shot. This mod goes particularly well with the Vectis as it has a one shot magazine, giving the bonus to all shots fired.
In addition to being 60% weaker than the Primed Chamber mod given to the top 100 players with the most kills after the Informant Event, this mod also occupies two more capacity slots. (6/7/8/9 on Charged Chamber vs. 4/5/6/7 on Primed Chamber)
This is an Uncommon mod from a relatively rare enemy type, regularly drops on T3 corpus survivals. However, it is found occasionally in treasure rooms in Orokin Void missions.