@BillRM,
Get real, the straw purchasers for guns are not usually some bum--plenty of guns are being brought by straw purchasers for the purpose of reselling them illegally to someone else, often someone who could not pass a background check, and plenty of guns bought and distributed that way wind up on the streets of our large cities, like Chicago. And the penalties to straw purchasers are currently very minimal, which makes it an acceptable and lucrative risk to take, and that's what's got to change.
We do have to better enforce the laws we have in place, and stiffening the penalties for making straw purchases, and for having gun sellers turn a knowing blind eye to such purchases, would be doing that.
No laws are totally effective in prohibiting people from violating them, but stiffer penalties, including incarceration, are a much stronger deterrent than a slap on the wrist.
If the goal is to reduce the amount of gun violence, then you use all the measures you can to do that--and putting better teeth in existing laws is one way of doing that.