That kit comes with a 6 place adjustable gas plug. You want to set it at it's lowest setting that will reliably cycle the rounds you are shooting. What you don't want to do is over gas the system and beat the bolt carrier into the trunion. (Especially a concern if you are using that reduced power spring in the kit.)
If you haven't drilled open your gas ports, then you probably can just close the setting on your gas plug to the right level for your high brass/buckshot/slug shooting and just open it up again for the bird shot stuff.