This is similar to ticket T1161, but involves shooting at hostile ships.
If I spawn a very tiny pirate ship of 15.4 mass and try to use a huge push beam on it, I am unable to move it.
416 Beam/416 Cannon/416 Push
1248 total size push weapon is unable to make a 15 mass pirate ship budge at all. I should be able to completely dominate a 15 mass enemy ship with a push weapon of that size, but they won't push back. They just stay anchored in place.