they are rather quiet......i shot a fully auto mp5 in 9mm.....without a can and with a can(silencer...)without a can it was as loud as youd expect....without it we safely shot it without earmuffs and the noise was less then a 22lr without a silencer...ive shot a fully auto 10/22 with a silencer and it was completly silent with high velocity ammo...all you heard was the action working.....dont gimme the crap that its illegall ect ect both guns were completley legal.....but i agree in the movies they make it sound TOO quiet.....probally because they are shooting blanks which barely make noise without a can.......