EDIT: On a digital food scale they’re slightly lighter than live 124gr ammo, less than 4/10 gram. Close enough for me.
Steelworx 9mm Luger Stainless Steel Snap Caps (10 Pack) https://www.amazon.com/dp/B07DDQTDKZ/ref=cm_sw_r_apan_glt_i_XHE40255VTBBKE7FYT65