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There has been an auction for one on ebay for the longest time.
*EDIT* ebay link deleted.

I actually got my own copy from a Thai version of the Target exclusive Hellboy 2 video tin. Turns out it...

Wall of Hellboy:
https://farm4.staticflickr.com/3876/14853954504_33c364c825_z.jpg

Upper right is a 3D printed Hellboy replica gun w/break-open, and 40mm round. The trigger actuates the hammer...