...Uh, mate, "Q" allows you to rack the pump. Weird mechanic, and it was frustrating for me the first time when I didn't know, but it is there in the description. (It does mean we may need a tutorial section, or at least, a menu to allow us to know what the control layout is, and if we want to change it to our own preferences.)
Still, I find shooting them in Spawn to be rather boring, as the fun is in prancing around with our current Protagonist and having her shoot all pell-mell in what is likely panic if she's a virgin.