There are major differences between the Salvation and the more common Emissary Heavy Artillery installation. For one, it has nearly twice the range of the Emissary, which in itself has the greatest range of all the factions' respective Heavy Artillery structures. For another, the Salvation fires once every three seconds or so, making it a very expensive base defense to support (about -7500 Energy per shot!). ALWAYS surround the Salvation in power generators and it will fire TWICE as fast even if they are T1 ones. There is no excuse not to.