Hey guys!
Let me bring some light to this topic
When we designed the Epic Properties, we gave them the enough amount of power so they could be the true protagonists of this Epic Forge update. This means we have to cut off some of the damage budget from the old forge properties.
Arsenal was probably the most problematic one, because in some weapons one simple bullet supposed a meaningful DPS increment so their final DMG was overpassing the budget. That's why we had to remove it from many weapons.
Hope this clarify your doubts!