The tommy-gun worked because the Borg Collective had never been shot at with a tommy-gun, not because some weapon from the 1920s is the holy-grail to defeating Borg drones.
That's kinda my point. Doesn't take a lot of fancy high tech weapons or tactics to defeat the Borg; they are vulnerable to just about anything they've never seen before. If they adapt to machineguns and/or projectiles, you hit them with flamethrowers; they adapt to flamethrowers, hit them with poison darts. They adapt to poison darts, hit them with phasers. They adapt to phasers,switch back to machineguns.
The Borg are many things, but they are not overly clever. They adapt to what you are doing, but they rarely try to predict your next move.