The ex-felons who really want guns to commit crimes are not deterred. If you think they are, I have a 2008 Presidential Candidate whose hope & change you'll really love.
Ex-felons who might want guns for normal purposes like self-protection (I know, this crowd doesn't like having certain classes possessing the means to self-defense) or hunting (ditto) or collecting (ditto).
The self-evident purposes of these laws it to harrass (today's) legitimate gun owners into giving up. Including the threat of entrapments like this to make them into felons, so their 2nd Amendment right can be taken away.
But hey, we're so far into the denial of the rights of "others" for whatever reason, thinking it won't be our own rights that get lost, it's hopeless.
It's even more powerful than "bread & circuses" because it sells to the "haves" not the "have-nots."
America -- a great idea, didn't last.
In most states, felons can have their rights restored, including the right to keep and bear arms. It does take some work, though.