Trying to identify a film by its gun

Howdy,

So I remember this film. I think it was a buddy cop flick. The basic plot revolves around a .50 cal submachine gun. They bad guy characters I think were portrayed as Germans or some type of Europeans, hitmen, gangsters, I can't remember. The big reveal in the film is that it turns out that these guns that aren't supposed to exist were hand made by the good guy's own firearms tech as a custom order. There is also a scene where the house our heroes have taken cover in is cut in half and knocked over by the gunfire from these things. That is all I remember from it and I've been trying to remember what it is for years. Has anyone seen anything like that? If so what is the film title?

-KJ