You can also try this if only you want, put this in the CfgWeapons section:
modes[] = {FullAuto};
class FullAuto
      {
         multiplier=1;
         burst=1;
         soundContinuous=false;
         reloadTime=0.0142;
         autoFire = true;
         useAction = false;
         useActionTitle = "";
      };
This is definately not guarenteed to work! It is only a suggestion if my above post doesn't work! Also, you may have to delete the other reloadtime.