Is that a new midway policy? The last time I ordered ammo from Midway (about the middle of last year), I had no issues. The only place I had issues was with Bass Pro shops. They do not ship to NJ.
I can only asume some of these companies are taking a more conservative approach and updating there corporate policies, most likely as rfkhunter mentioned to cover their ass.
I use to order a ton (not far from the truth in weight) of ammo from Cabelas, but unfortunalty it seems they've updated their free shipping promos to exclude ammo.