Attachments have changed greatly in Season 13 and need to be manually redone on the site. This will take quite some time, so apologies if this section isn't helpful right now.
Attachment Details
YKM Light Barrel (Long)
Barrel
Added in version 1.0.15.0 1.0.15.17
Extended barrel with slightly increased weight to improve stability and increase firing range. Effective at medium range.