User blog comment:Owlfeathers0117/New RP Weapon Classification System/@comment-10905876-20141229191700/@comment-11135771-20141229200441

Maybe... it still seems kinda fast to me though; I mean, modern railguns firing projectiles that are tiny compared to those of the Spire of David installations have a muzzle velocity of up to 3500 m/s, and the speed of light is 299,792,458 m/s. If the Spire of David's projectile was just one kilogram in mass (tiny, relatively speaking; a Mk.45 gun fires a 32 kg shell), a round moving at 40% of c would have a kinetic energy of around 1.7 megatons.

How heavy are the projectiles it fires?