It would take an extremely large and expensive accelerator to fire it at any meaningful speed, couple that with long re-load time and the costs of getting tungsten into space and then melting it and then just shooting it away and i think that just using a gun may be better...

I'd like to know the science behind this. I have a few more specific question that I didn't want to put up in the main question. A) The cooling rate of molten metal in space. I have heard that heat dissipation is an issue in the vaccum (with no medium to radiate heat into), and that this is why the space shuttle usually keeps it's bay doors open (at least during the daytime). Is this actually the case? There seems to be some dispute, especially since a friend of mine (who is a physics student) has said this on many occasions, but when I asked him this particular question he brought up the idea that molten metal cools fast. Would this be true in a vaccum? B) Whether molten metal could be magnetically accelerated in nearly the same (or in any functional manner) way as solid metal. C) It's effect on an armored hull. I know for a fact that many anti-tank weapons used molten metal created by an explosive to burn through armor plating, and I imagine that using Tungsten (which has the highest melting point of any metal) would be quite effective. My main thoughts are on whether the kinetic energy of the impact of the molten metal would also be significant. Since range isn't an issue as long as it can, indeed, be fired from a weapon and it doesn't cool off before it gets there (in which case it'd be a slug anyway), I think it should work well. Really, I am kind of confident in the feasability of this, but I wanted some secondary opinions because I can't seem to get them in the usual places. Mind you, whether people would actually do this is kind of irrelevant to the discussion because it is sort of in a sci-fi context, but I prefer hard sci-fi in certain specific areas (like weapon's technology). Since real arsenals are made up of a variety of weapons for different purposes, I am not discounting obvious weapons in space such as railguns, lasers, particle beams, or missiles. Thanks for you answers.

The context of the question was such that it assumes the economic difficulties of advanced weaponry in space are no longer difficulties, or are at least mitigated by a substantial extraterrestrial infrastructure to allow for said weapons, so assuming that the economic difficulties that are obviously inherent in any space weaponry are acceptable or non-existent, I'd like to know the technical viability of such a weapon.

I personally think that it would work. In a vacuum, possibly in space, there is no gravity, and once something is accelerated, it will continue to move unless some other force acts on it. However, molten metal will cool down immediately in space as the heat radiates away. According to the second theory of heat energy, which states that heat always goes from a place which has higher temperature to a lower one. But the metal would still cut through an object in space when provided enough magnetic propulsion. And actually, any metal would do.