Rate of Fire
From Da Rules:
Many handguns are capable of firing 2 or 3 shots per round.
Firing one shot allows for a more careful aim and steadying
of the weapon. Firing more than one shot places speed above
accuracy. When firing two or three shots in one round, roll for
each shot individually, with all shots receiving one penalty* die.
*Since I had to look this up (more familiar with older editions of CoC):
A bonus or a penalty die is an additional tens die rolled with the two dice rolled for 1d100. So three ten sided dice are rolled. One is designated the single digits the other two are designated the tens dice (10, 20, 30, etc.) In a bonus die situation you get to count the best tens die option as yours. In a penalty die situation you count the worst (in this case the highest) roll as yours.
Notice that the dice roller at RPOL is not very good at doing this. You will have to roll each 1d10 individually, designating which one is the single digit dice in the Reason for Roll. If you forget to designate, or if you just want to roll 3 x 1d10, we will assume that the first dice rolled is the single digit die and the next two are the tens dice. Remember to check the box in the roller that records each die!