Erm, actually, the Holodeck includes replicators that create real object to interact with as well. Therefore, those Tommy Guns "could" have been firing real projectiles if the holodeck program decided to do so with the safeties off. Of course, they don't actually tell us

In any case, I was of the impression that the Borg drones were killed because they were adapted for phasers and not projectiles. That's why Picard and Co had to hightail it after killing the drones since the next wave would probably have adapted to the tommy guns.
And this isn't even teleportation. They just replicated the state of a particle onto another particle. If anything, it'll be a thought experiment to decide whether the copy will be "living" and "thinking".
A thought experiment since it'll never happen within our lifetimes.