How many illegal gun owners in U.S. 2012
There seems to be a problem getting the criminals to admit to owning illegal and stolen guns.
Is it possible to know if they are illegal?
you would need to check the records for how many criminals used stolen guns to get the answer. Law abiding citizens who own guns are not on record
More then anyone will ever know. and you'll never get rid of them either. Make all the laws you want they obviously don't care about following them.
All of them
Criminals don't follow laws so all of them