Or, something that doesn't allow people to totally cheat with that 5000 range (it will show up as 5000, and still go 5000; acquisition range is just where the hero actively attacks hostile units) try triggering it so that you have an upgrade based on "Long Rifles" that affects the hero be upgraded depending on the buff the hero has. Make it an aura with 0 bonuses, have different (yet identical) buffs per level, then make it so that when a hero learns the ability, that player gets the upgrade set to the appropriate level.