A weaker spring. Heavier BBs can sometimes help, but I find that they just "punch" rather than sting.
The best way is to simply wear better protection. If the clothing is tight to your body it will hurt more as well--a loose or baggy shirt will absorb the impact.
The best way is to simply wear better protection. If the clothing is tight to your body it will hurt more as well--a loose or baggy shirt will absorb the impact.