Hi, new here and just bought a fnx 45, first FN gun. I was wondering if anyone knew if I were to get my slide milled for a red dot if I will need the sights off the tactical version for co witness to work properly? I have a Burris fast fire 3 waiting to be put on and I don' know a whole lot about pistols . This is my first and I would like both open sights and red dot working on it. I thought the tactical version was a little to big so I went with the regular fnx 45. Anyways does anyone know if I will need new front and rear sights and if so what kind and size should I get or should I just get factory fnx tactical sights, if they can be ordered ? THANKS