Free: Contests & Raffles.
Is your custom rifle for long range? If so the Zeiss and Swarovski won't get you very far. Not enough internal adjustment. For hunting purposes all 3 are fine.
only because Ive seen so many guns three plus inches high at a hundred . I like to know that with the turret I can set dead on at 100 . if your only shooting 400 plus then a20 my be for you.