Behind-the-scenes at US rifle convention in Texas

The gun rights lobby in the US, the National Rifle Association, is holding its first convention in Texas since December's shooting at a school in Newtown, Connecticut.

The massacre revived the debate on firearms, however the NRA helped defeat a proposal to tighten gun controls in Congress last month.

Jonny Dymond reports from the exhibition hall of the NRA convention in Houston, which he says is the ''beating heart'' of the whole event.