Brace height specs from a bowyer are just to give you a starting point for your tuning. No two bows are going to be exactly the same, no two people will shoot a bow the same. Your shooting form/release can affect your brace height. Sometimes different arrow weights will change your brace height. Changing string material can change your brace height. Whenever I see someone asking for a brace height for a particular bow it makes me cringe. This isnt rocket science, just start at about 7.5 for recurves and R/D longbows, 6.5 for D bows and tune for your arrows.