I am sure many of you have seen this before but there are a few problems with it.

People usually cite this scene as evidence for that.

But the rifle and bullets are holograms. In Star Trek that would mean they are made out of force fields and light. So are going to operate differently than a normal kinetic weapon.

Another thing to think about, is when the first drone got hit it went down almost immediately (also notice Picard's horrible aim). Whereas the second drone kept on moving toward Picard even after somewhat sustained fire. This could be implying the Drones were already adapting to this "new" weapon even despite the fact they would have been part of a very limited collective (compared to normal Borg) at the time.

So even if this was considered a normal kinetic weapon it clearly wasn't going to remain effective for very long.

I don't believe we ever actually see a Borg Drone shot at with a projectile based kinetic weapon. So the question is somewhat up in the air.

Now if you wanted to say "the Borg haven't adapted to knives therefore they can't deal with projectile weapons" you would have a bit more ground to stand on.

Standard 24th century drones don't have defenses against knives.

That being said, pretty much any depiction of ST force fields includes the ability to stop physical objects so the technology definitely exists in universe to adapt to that and create knife immune drones if that kind of thing became a major problem.