Actually it would help greatly in finding those who are second hand selling their guns to ppl who shouldn't have them. 

Every gun that's found in a case like this, where the owner reports they sold it to another person would be one less person able to get a gun and likewise unable to sell them illegally. 

Not all people who obtain guns legally are law abiding. That's just a fact.  If you want to own a gun (and I have one as well) then that's not a problem.  However I see no issue with having a registry because I don't intend to ever break the law with my firearm.  Seems to me ppl against the registry are ones who are trying to hide something.