Can be found in SMG/Rifle - Battle Rifle.
Cei-Rigotti really only became famous thanks to Battlefield 1. Aside from its mechanical aspects and some information on its designer, the rest of its career is covered with mystery. No one knows why it never saw any adoption.
While it fires 6.5 Carcano rounds, it doesn't share the same en-bloc clip that is used in Carcano pattern rifles. This mod adds Cei-Rigotti's own proprietary stripper clip to load with.
As usual with most of my firearm mods, this rifle also has invisible rails. Don't let your bubba dreams be dreams.
Open the .zip and extract Greys_CeiRigotti_BF1.deli into steamapps\common\H3VR\BepInEx\plugins\Deli\mods. Rest of the zip content are there for Thunderstore compliance, and not needed for manual install.
The Cei-Rigotti model and sound are ripped from Battlefield 1, developed by DICE and published by Electronic Arts. I do not own any of the assets.