What aspect of crime? Commission? Disuasion? Severity? What kind of crime?All in all, no one has any clue how gun control affects crime.
It's a rather open-ended statement, though one can reasonably infer that, if you have more gun control and assume that bad guys will continue to use guns that, in fact, MORE crime will occur in the form of bad guys illegally obtaining guns as the only people who obey laws are law-abiding citizens.
If it's prevention during the commission, the largest variable would be the number of people who don't report a thwarted criminal to the police. I'm certainly no mathematician, so I certainly wouldn't want any type of job trying to map this out.