My first game out I was a little worried about how much pain this sport may inflict, But like every one is saying once your out there running and gunning, you dont really notice the shot enough to care. I have been hit really close with upgraded AEG and you get a nice sting factor but no more than a bee sting.
I was in the 2nd drug lab and some guy shot me through the window with a upgraded Ak47 and smoked me right in the lip, That stung because it split my lip wide open. The time it took me to get to the ground my face was covered in blood. All I did was grab a handfull of snow and the pain went away. Had a fat lip for awhile but no biggy.
Regardless I played the rest of the day, If most think about it the most pain you really feel is when you do something stupid like dive on the ground and have a mag pouch jab you in the diaphram, or slipping and falling.
Go out to a real game and then you will know what it feels like.