If you can't get black spindle then you can grab yourself a 1000-Yard stare for 150 marks at the vanguard quartermaster.
It's pretty much a mini black spindle due to its similar stats, solar damage and perks.
Vanguard quartermaster 1000 yard stare perks:
Triple tap (1 round to mag for free) perfect balance and mulligan.
Black spindle perks:
White nail (3 rounds to mag from reserve) perfect balance and mulligan.
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How to get mini black spindle: Run Crotas End on normal and get black hammer