@Jamiet99uk,
despite me adamant belief in the Right of the People to keep and bear arms, I would have a problem with any citizen, even a law abiding citizen owning a functional bazooka for self-defense. My reasoning is that a bazooka is NOT a weapon used for self-defense, it is a weapon used for destroying hard targets like tanks and bunkers. Further, the training needed to accurately and effectively use a bazooka is significantly more substantial than "small arms" traditionally used in self-defense. Bazookas, and other explosive weapons, are NOT effective at close combat/self-defense.
In addressing the OP's question, my "red line" is I think every American should be allowed to own a pistol (revolver or semi-auto), a shot gun, and a rifle (bolt action or semi-auto) with a scope. Beyond that, the weapons leave the realm of self-defense, and begin to cross into "offensive" weapons. Of course, the weapons listed above COULD be used offensively to initiate violence, but the right of self-defense MUST be maintained, and these weapons assure that. So, to me, a fully auto Uzi is not something that I think is necessary for self-defense.
As a bit of an aside, I think that every American should have weapons training whether or not they intend to own a weapon.