Hmmm...I'd forgotten the missing crank with my Barrett. Mine came with the factory cocker installed, but missing the crank.
I ass-u-med one could be found on line, ordered seperate from Barrett, e-bay, whatever. Apparently, virgin pre-64 Winchesters are more common than a crank handle by itself...
With the cocking rope, it was a non-issue, but if I had to rely on the factory system, it was a nonstarter.
YMMV, just something keep in mind if you get offered a great deal on a x-box without the crank.