Open the BS_ADS_Rifle blend space then right click each one of the animations on the blend space grid and change all the animations to ADS_Idle_Rifle.

If you dont know how to do this there is a video below.

Next open the BP_M1982 in the class defaults inside the Range Weapon Animations there is a variable called TP ADS Jog Blend Space, Set this to BS_Aim_Rifle.