After landing some Sticky Bombs on a friend last night, I kept noticing the damage being really low. So with the help of a friend, we tested some of the main explosives to see how much damage Lars was resisting. It turns out that instead of Lars receiving 60% explosive damage resistance (a value seen from the January 17th patch notes), he's receiving 90% explosive damage resistance. The Bigger Explosions buff of +100% explosive damage accurate reflect the damage resistance value for Lars being at 90%.
Landmine: Normally deals 140HP, but against Lars it does 14HP
Sticky Bomb: Normally deals 100HP, but against Lars it does 10HP
Hot Potato: Normally deals 100HP, but against Lars it does 10HP
Normal Bombs: Deals 50-70HP, but against Lars it does 5-7HP