Not sure what the percentage is on red border weapon drops for this season but I've barely gotten any even though I've already reset my seasonal rank. I've gotten maybe 5- 7 total red border weapons (not the unlocked pattern for them just the solo weapons) and doing Rivens Lair isn't even dropping weapons anymore. This is probably the first season that they just aren't dropping. Not sure if this is supposed to happen or it's some kind of bug.