The "Sleeping Giant" SMG in Borderlands 3 has the following white text:
Reloading has a chance to grant weapon bonuses
I have been running with it for a while and have yet to figure out what these elusive "bonuses" are. Will I be notified when it is triggered? Are the bonuses subtle damage boosts? How does this gun work?
You won't be notified at all. The bonuses vary wildly from 3x damage to 2x fire rate. But some aren't buffs. A few people have reported a drop in damage. I can't say I have ever had this happen personally. The way the gun works is every time you reload it you get a new random bonus until you reload again. As far as I can tell there is no way to predict what bonus it will take.
On a completely different note, this thing gives a good bonus paired with the Moze's "Some for the road" perk, which alone is quite powerful.
