ORIGINAL: Roskoe
I shot a wild turkey in April with an Easton FMJ - one of the toughest arrows out there. With about 2/3 of the arrow sticking out his backside, the bird was able to thrash around and break it off. It did not, however, splinter like a carbon arrow tends to do.
Thats the beauty of them... and ACCs. You won't get one through the arm. However I personally think the FMJs aren't exactly as tough as they sound... I had an experience. Its not really a relative archery experience (I dropped a rubber boot on one accidentally and collapsed it like a drink straw in a thick milkshake). They aren't designed for it... but I was suprised how little it took to break one.