Not clear to me what an "illegal gun" is. Do you know? Maybe there are gun owners who have lost the right to legally own a gun because of a felony conviction, but to say a gun is illegal in and of its own right is just wrong. The Second Amendment is quite clear, except to those who have a strong desire to get around its plain meaning.
The terminology should be changed to illegal ownership of handguns.
Only cases I would consider are:
1) Convicted of felony (we take away voting rights so this is consistant)
2) Immigrants
3) Minors without parental consent and supervision
Yeah, the owners complied with un-Constitutional state and local paperwork schemes and fees.