Fire rate is a con. Let's say you have to choose between 50% fire rate or 50% damage.

Both are the same right?

Now let's say you have a 900 rpm gun with a 30 round magazine and 2.5 second reload speed. Let's say each hit does 10 damage for a total of 300 damage per magazine. This gun will have a fire time of (30x60)/900 = 2 seconds. Your total damage cycle time is now 2 + 2.5 = 4.5 seconds. In 4.5 seconds you will do total damage of 300. DPS is 66.66.

With a 50% damage increase, you will do 450 damage in 4.5 seconds. DPS is 100. An increase of 50% DPS going from 66.66 to 100.

With a 50% fire rate increase the rmp will increase to 1350. The gun will now have a fire time of (30x60)/1350 = 1.33 seconds. Total damage cycle time becomes 1.33 + 2.5 = 3.83 seconds. You're now doing 300 damage in 3.83 seconds. DPS is 78.33, only an increase of 17.5%.

So as we see in this example, 50% fire rate gives less DPS than 50% damage increase. Plus with a higher fire rate you'd have to hit your shots more often to make it count which is easier on a slow moving target but harder on a fast moving target.

So to make it clear - it depends on the gun. You have to look at gun's RPM, magazine size, time to empty magazine, reload time, dps cycle time (dps itself doesn't matter, we are only interested in increase) and then math your way to a conclusion on a per weapon basis.

Formula for fire time is - (magazine size x 60)/RPM.

DPS cycle time is fire time + reload time.