Editing Warhammer 40,000/7th Edition Tactics/Imperial Knights (section)

===Ranged===
;Rapid-Fire Battle Cannon
:A two shot Leman Russ Battle Cannon, ever reliable and perfect for clearing big units of MEQ or worse, since that's two large blast markers that can cover a whole lot of dudes. Also, since it's ordnance, you get four chances to penetrate vehicle armour (due to the Ordnance re-roll).
;Thermal Cannon
:A shorter ranged, single shot pie plate that is S9 AP1 melta. So you use this for wrecking Terminators and Land Raiders. Against most other things you were probably better off with the Battle Cannon instead. Mathhammer confirms this, the battle cannon is statistically better against every target with the exception of AV14 in melta range and TEQS.
::Do pay attention to that AP1, however. You get a 1/3 chance of destroying a vehicle rather than stripping a hull point as well as the ability to cripple a tank into submission.
;Avenger Gatling Cannon
:S6, AP3, Heavy 12, Rending - For absolutely ruining squads and/or light vehicles, especially if your opponent tends to space his units further apart to prevent them from suffering under blast markers. Can even be used as an AA weapon in a pinch due to its high rate of fire but you've got other weapons for that now. Due to rending and high rate of fire eats HP like popcorn, a built-in heavy flamer for mobs, and being best option against AV, even better than the thermal cannon against every possible target.