There isn't.
It uses an Upgrade Long Rifles to increase the unit's Attack Range.
Note that this is NOT an ability, it is an upgrade, which means you can't simply add and remove it from that unit/item.
To decrease the range, simply create another upgrade of same version but make its value negative to counterbalance the added range bonus.
It's quite complicated to add/remove it that's why in DotA, Sniper and Enchantress gets a perrmanent upgrade from Attack Range Bonus (Sniper passive skill, Enchantress cannot drop her Scepter).
It uses Ability Level of that Upgrade to alter the unit's Attack Range and that can be its limitation (you won't put a 100 Level Upgrade, would you ?).
Also, by doing an Upgrade, it affects all units that have this Upgrade, it can't be on one unit, it is applied to a unit-type.