Not sure how you "tested" this. The Black Spindle, according to a comparison video I just watched, does approximately 30% more damage when consuming all ammo in reserve and without reloads. Now the sleeper does more Damage Per Second for 3 shots but once you factor in reloads it's DPS drops significantly. Missing a sleeper shot is more detrimental than a black spindle shot as well because you lose a far larger chunk of damage to error. The 1k stare does less damage per hit but fire rate allows it to have pretty solid DPS. Unless you have hard numbers that prove otherwise I doubt that combo is better than my current setup with the Black Spindle and equipped heavy. I've also used 1K stare (minus triple tap and casket mag) and Sleeper and prefer the BS over it. The margin of error with sleeper could be huge and no one is perfect.