Orient the bolt just like in the picture.
Grab the black, depress the detente with your thumb, and turn it clockwise hard. Make the cocking piece “slide” up the ramp and cock (your second pic).
Basically, grab it and twist it hard.
"What we obtain too cheap, we esteem too lightly: it is dearness only that gives every thing its value. Heaven knows how to put a proper price upon its goods; and it would be strange indeed if so celestial an article as freedom should not be highly rated." Thomas Paine
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