Since we built the mod to be as realistic as possible, we use real-world data. All of the in-game ammo weights, with the exception of the 88mm shells, are accurate to within a few grains. So yes, a single round of 20x102mm really is that damn heavy & if you think the 88mm stuff is too heavy, be glad ‘Sheep overruled us there. They were originally 10 lbs heavier per round. If it bugs you, either ask someone to make a patch or just don’t play on Survival.