I freely admit I don't use ogryns; the models cost too much in currency and so far I can't be arsed to convert Ogre Kingdoms models for it. But five Ogryns fit in a Chimera, and their guns are moderately scary. Alternatively, loading them up with a primaris psyker can make it difficult for the enemy to shoot at them as they go up the board thanks to Nightshroud, and a screen of Guardsmen in front of them (conscripts, perhaps?) goes a long way toward giving them cover from enemy shooting if that fails. Tactics matter in this game.