The ones we had would penetrate the skin, I had one that looked like an old Winchester and it would roll a bb under the hide if you hit an area with no clothing on it. Can't tell you the amount of times my mother got on me for having bb's under the skin.lol course you just had to roll em back to the hole and they come out.
My grandson is into this paintball and airsoft stuff, He has welps on him from shooting each other at these games. I will say they do wear head and face protection. I talk about him, but we did worse.lol He wanted me to go and play with them one day. I said I don't think so and if you ever shoot me with that damn thing I will beat yer ass.lol That one airsoft gun is fully automatic and flings em out so fast you can't even see them till they get way out there. That sucker would hurt.