One of my arrows has a Muzzy Phantom 220 grain tip (242 w/insert). I practice with a 200 grain field tip. There is a 17% FOC on my 534 grain arrow. Now, this is totally UNscientific, but when I switched to these 534 grain, 17% FOC arrows they penetrated very differently than the lighter arrows I was using with a 125 grain tip (about 140 w/insert) with a 11.5%FOC. The 17% FOC arrows routinely come 6+inches out the back of the bag targets and also penetrate the rinehart deeper. Like I said totally unscientific but from what I have seen with the heavy arrows with a larger FOC % I am sold. The other day I was measuring the speed and the numbers went like this:
[ol][*]0 yds - 234FPS[*]20 yds - 228FPS[*]30 yds - 225FPS[*]40 yds - 222FPS[*]50 yds - 219FPS[/ol]
I like these arrows and I am sold on a heavy arrow with a high FOC.