Could be that the broadhead is a little heavy for that type of arrow because the flatlines by easton are made for speed and more target shooting. It may shoot okay with fieldpoints but with the blades on the broadheads its catching more wind than the fieldpoints. I dont know much about the twister vanes you shoot or how they group but i recommend blazer vanes by bohning caus they are a stiffer fletching and if you shoot a heavy broadhead you will most likely want to shoot a heavier arrow. if you want a carbon arrow i would recommend either easton axis or carbon express pile driver.
125gr tip with lumenok and twisters = FOC of 8%...I will check arrow flight again after I get new practice blades...I'm so curious, I might shoot the actual broadhead tonight...if it's not raining!
Calculating the FOC for 125gr tips with lumenoks and then with the microlite HIT nocks the arrows came with I came up with these results...
125gr tip w/Lumenok FOC = 8%
125gr tip w/Microlite FOC = 10%
100gr tip w/Lumenock FOC = 6%
100gr tip w/Microlite FOC = 8%