To add the scope in function you must edit weaponrailgun.meta in
mods\update\update.rpf\dlc_patch\spupgrade\common\data\ai

Search <DefaultCameraHash>, and replace DEFAULT_THIRD_PERSON_PED_AIM_CAMERA
with SNIPER_AIM_CAMERA

Search <CoverReadyToFireCameraHash>, and replace DEFAULT_THIRD_PERSON_PED_AIM_IN_COVER_CAMERA
with SNIPER_AIM_CAMERA

Search <ReticuleStyleHash>, and replace WEAPONTYPE_RIFLE with SNIPER_MAX
Under this line, add SNIPER_MAX to <FirstPersonReticuleStyleHash> like this

<FirstPersonReticuleStyleHash>SNIPER_MAX</FirstPersonReticuleStyleHash>