My Badger mount does not have to mount in a slot. You have to slide the Badger mount on from the front or the back. The Nightforce mount is a 2 piece clamp I believe and you don't have to mount that in a slot either.
Thanks Magman! I only asked because the particular base I'm using does not have cross slots from end to end completely. There's a good chance it'll need mounted where there isn't a slot.