"BF" is 1995, according to the Italian gun date code charts lurking around the Internet.
It seems likely that it's an Armi San Marco - they marked some of their guns "SM".
Like Hellgate, I've got a few guns with some pretty good pitting and pretty light rifling. With just one or two exceptions, it seems like as long as there's a bit of rifling to engage the projectile, that's enough. For example, in my great, great grandad's 1861 Springfield rifle that he carried in the Civil War, you can feel that about half of the barrel has enough pitting to make the minie ball go in kind of rough. But there's enough rifling in there to stabilize the ball so that it's more accurate than me out to a few hundred yards.
I would do what I could to remove any active rust. Pitting, there's nothing to do about, the damage is done. If you get to the point where it just seems like you're never going to get clean patches out, try shooting a few rounds through it, then give it a good cleaning. That's worked pretty well for me several times.
Well we don't rent pigs and I figure it's better to say it right out front because a man that does like to rent pigs is... he's hard to stop - Gus McCrae