Municipalities have laws concerning air guns. I think Somerville specifically say they can’t be discharged within city limits (I certainly have never tested an airsoft gun within the confines of my own home…) Various places in the metro area have differing weapons laws. It’s okay to carry a loaded pistol (if you have a license), but that better not be a Swiss Army knife with a 3” blade in you pocket next to you legal preban high capacity magazine.

Slingshots are illegal to sell in MA, whether they are legal to personally own isn’t really settled law (nor will it ever be since no DA in his/her right mind is going to bother getting a conviction for a slingshot).

No laws against pellet bows though.