10 sternguard with 2 heavy flamers, 2 combi flamers, and 6 combi meltas drop poded and combat squaded can take out 2 units of armor on turn 1.
About exactly what I am modelling up for my salamanders, just no combi flamers. And I blew up two preds on the drop the first time i playtestd the unit (one had Kronus in it too boot). It is serious anti tank for sure.
I don't have the codex in front of me right now so I'm not sure if the lascannon toting SG are able to keep their bolters as well but if I had to guess I would say they do.
They keep bolt pistols -- have to exchange the bolters unfortunately. Its why the heavies are cheapish for the squad.