No hammer of course. At Primary Arms.
https://www.primaryarms.com/Fail_Zero_M16_Basic_Kit_EXO_Bolt_Carrier_Group_N_p/009-fzm16-4-01-nh.htm
https://www.primaryarms.com/Fail_Zero_M16_Basic_Kit_EXO_Bolt_Carrier_Group_N_p/009-fzm16-4-01-nh.htm