The 2000 physical resistance make the modded rockets (with 60 physical damage) useless against asteroids. (Rocket turrets will fire the whole magazine at any incoming asteroid since they are too stupid to calculate the area of effect damage.)
Please change the normal rockets to direct explosion damage and give the explosive-rockets the AoE-damage. – At least when space-age is active.
I hate the decision that there is exactly one type of ammo against each enemy. But factorio devs made it that way and now you can not change base game ammo because it will mess up everything.