Were you standing in exactly the same spot for all 23 of those shot? I imagine that you probably were not. So in the process of moving to a better location so that you can continue to get precision hits you likely walked over a couple special ammo blocks which would have filled your ammo back up. The way black hammer is now it functions as an exotic without actually being one. It is basically an exotic weapon that you can equip with another exotic. That should not be the case. So changing it in this way moves it back into the realm of legendary. It will still be one of the best sniper rifles.