The WA Police Union has urged the state's new top cop to equip metropolitan officers with long-arm rifles to be able to deal with the possibility of a mass shooting such as the recent attack on concert goers in Las Vegas.

The WAPU has made a fresh submission to Police Commissioner Chris Dawson to equip Perth based cops with long arm guns, such as AR-15s.

The highly trained Tactical Response Group have ready access to long-arm rifles.

At the moment only country based cops and the highly trained Tactical Response Group have ready access to long-arm rifles.

A similar submission by the union was knocked back by the previous police commissioner Karl O'Callaghan.