It can do in some cases depending on where you are hit and the power and proximity of the gun. Generally, it you are hit on the bare skin you will feel a sting. This is more noticeable on skin over bone and less so on fleshy areas.
NOTE: If you have played paintball, a comparison would be that the BB’s hit with approximately 10-20% of the force of a paintball pellet.
BB’s will leave a mark like an itchy-bite which fades after a few days. We advise players to cover up when they first start playing Airsoft until they are use to being hit. Many veterans will play open field events in short, tee’s and safety specs as they are use to the hits or don’t get hit very often. If you don’t want to look like your had a wrestle with a hornets nest, cover up and wear full face protection!
Clubs limit the power and engagement distances of guns on the field to try to minimise discomfort.