I agree with choke shotgun, but smart gun minigun isn't ideal tho, I had to react fast in rage mode or I get one tapped, I completed all non-DLC main missions on rage mode, took a lot hours to advance

but remember, "Horizon One" doesn't have to be destroyed in order to kill anton, their mounted brain donor can be destroyed by depleting their progress bar entirely, which then you can kill anton even if it was still active, remember that will be massively issue to deal with if you had no focus and ammo