The Legendary Core Armor Can Hold a Lot of Ammo and Grenades
16 slots for Ammo 8 slots for Grenades
It seemed like I could equip 4 primary weapons, but that got a little glitchy with 3 and one of the weapons fell off after a short bit.
Visually, the Grenades and ammo start to stack directly on top of previously equipped grenades and ammo (visually you only see 4 grenades and 8 ammo cartridges, but you can use the full amount).
Still has 40% armor reduction, like other heavy armor.