blud, u can only get cdm substat from muzzle, they dont put cdm on other attachment beside muzzle, thats why i said in my comment go for atk%/atk/cr/cdm for ur muzzle, the rest for other attachment is atk%/atk/cr.
beside from muzzle, u can get cdm from weapon, fixed key, common key, its useless even if u have high cdm but low atk