That's known as firing from the "retention position".
One thing that one certainly does want to avoid--in any scenario--.is shooting the weak hand or arm. If one is blocking blows with it at close range , there is a real risk that it will be moved into the way. You probably want to get the arm out of play before shooting.
Here is a pretty good video on the subject. I do not see the trainer shooting at the pelvis, and he is not stepping backward.
One more time, there is no way to reliably predict the immediate effect of any shot on an attacker.
One thing that one certainly does want to avoid--in any scenario--.is shooting the weak hand or arm. If one is blocking blows with it at close range , there is a real risk that it will be moved into the way. You probably want to get the arm out of play before shooting.
Here is a pretty good video on the subject. I do not see the trainer shooting at the pelvis, and he is not stepping backward.
One more time, there is no way to reliably predict the immediate effect of any shot on an attacker.