Dropped the rounds as suggested by @mercer Played without other mods.
Played 2 matches: First was Black Crusade Battle Mission agaisnt Chaos. Tacs managed to kill a Demon Prince of SLaanesh in that one. In melee

Put the Sternguard in a bunker on turn 2, played them defensively.
Second match was a Surprise Attack vs a Guardsmen. Drop Pod went empty inside of the enemy encampment, sternguard provided fire support aloing a side of the Land Raider. Guard was completely mechanized, but I did not really feel the lack of anti tank, by turn 5 only 1 Demolisher out of 2 demolishers, 3 chimeras and a manticore, was standing.
I might put the Multi Melta on the Raider if I find suitable modelling material for it. Could use that 10 points from the cap on that.