In Borderlands 2, Jakobs guns say that they fire “as fast as you can pull the trigger.” However, they don’t all have the same fire rate. What does this mean? Are the fire rates actually different, or are they effectively the same?
You are correct, Jakobs brand weapons are semi-automatic and will only fire when the trigger is pulled, regardless of how fast that might be. Fan that hammer, cowboy.
However, there are some exceptions to this. White and Blue-rarity Jakobs sniper rifles are bolt-action and thus are affected by the rate of fire stat. The higher the RoF stat the faster the bolt is cycled. Likewise, the Gold-rarity Jakobs sniper "Goldfinger" is also bolt action and is affected by the rate of fire stat.
The rate of fire statistic does not have any affect on gameplay except for those few rifles mentioned above.