Dave Kopel is not an unbiased source for this kind of information and in this specific instance I can testify first-hand that the facts have been "massaged" to convey the image he wants you to have.
I am a member of the Oklahoma National Guard and I am in New Orleans right now. I'm working in the Headquarters for Task Force Orleans and I have access to the J-3, J-2 and the PAO for confirmation on all this.
Three have been, and to my knowledge still are, confiscations of firearms going on. As we enter buildings, when firearms are found they are removed from the premises.
Here's what Mr. Kopel isn't telling you.
One of the events early on in this city was a great deal of looting and one of the commodities most sought was firearms. In every case were we find firearms (and many were found, not in homes, but simply in the streets) they are being collected and turned over to the ATF.
ATF is running traces on all the recovered weapons. When their legal owners are determined, the weapons will be returned to them.
This is far more a matter of firearms restoration than of confiscation...but that doesn't fit Mr. Kopel's agenda.
Our job, as National Guardmen, is to support the local authorities. The orders for this came from local law enforcement. The federal authorities could not have given such an order, and if they had, we would not have been bound to follow it. This is the consequence of the Posse Commitatus Act.