http://www.egscomics.com/d/20020515.html
I find it interesting that Grace seemed to be knocked back by the beam in this comic whereas in the previous cat transformation she was able to stand point blank with the thing and not even noticeably flinch. For that matter the BOOM in the third panel definitely suggests some concussive force at work. Maybe there was enough mass distortion to have some kind of effect like that? It's kinda weird how it almost looks like it was the scan-beam that knocked her back. Well, the exact workings of the gun have likely changed so much by now it doesn't even matter, but it still doesn't make that much sense.
I hope Mr. Verres didn't pay to much for that shirt. I mean, if it was just a single rip it might be repairable (although she'd probably want to wear a jacket or something to hide the stitching), but that sucker was shredded.