To enable barrel customization, weapons need to include WCMT_ForeGripAndBarrel (type 20) rather than separate WCMT_ForeGrip and WCMT_Barrel components (type 5 and 6, see component types).
This is GR5_Component::GetAttachableCompType (0x10121A30, AI.dll) that maps the component types to component customization grid UI:
To enable barrel customization, weapons need to include
WCMT_ForeGripAndBarrel
(type 20) rather than separateWCMT_ForeGrip
andWCMT_Barrel
components (type 5 and 6, see component types).This is
GR5_Component::GetAttachableCompType
(0x10121A30, AI.dll) that maps the component types to component customization grid UI: