Handgun crime figures, not airgun, I know, but it shows how a ban can work:

Injury by being fired, used as a blunt instrument or in a threat

1996 - 279 (Dunblane)
1997 - 393 (Ban)
1997/98 - 317
1998/99 - 239
1999/00 - 352
2000/01 - 400
2001/02 - 648
2002/03* - 640
2003/04* - 590

Figures from Gun Control Network web site.

Something to keep in mind.

Keith