Granted. It would be difficult to create rail guns that fire at those velocities. So, let's do some more calculations:
3% light speed (about 9,000,000 meters/sec) would decrease our overall kinetic energy to 4,131,000,000,000,000 joules, or 4.131 X 10^15. Which equals 4,131 terajoules, or 4.131 petajoules. For comparision, 4.184 × 10^15 joules (or 4.184 petajoules) equals 1 megaton, or 1,000,000 metric tons of TNT. Using the same five shots per second firing rate, the Abydos can deploy ten megatons a second against enemy targets-Still very effective against Al'kesh and other small threat vessels, such as Wraith cruisers. And far more practical weaponry for a ship this size. Naquada-enhanced shells would, for a given amount of naquada, make these rail guns extremely effective against enemy capital ships. However, we do not know exactly how much. What do you think?