If an animal twists while an arrow is going thru it, it is reacting to the shot (either sound or movement), not the arrow impact. Even if the ribcage is 24" wide, an arrow going 180 fps is going to be thru the ribcage in 11/1,000ths of a second. At 250 fps, it will take around 74/10,000 of a second to pass thru.

Sitting with a watch in my hand set on chrono mode and punching the start/stop button as fast as I can, my best time is 13/100ths of a second. Now, I know exactly when I punch the button and know that I have to punch it again, immediately, so my reaction time is geared up. Ideally, you should be shooting at a relaxed animal. So, the deer won' t know when the arrow will hit and will be a complete suprize when it does, and that will make reaction time slower. So, the arrow will hit and SHOULD be in the dirt on the other side at least 10 times faster than the deer can react to the impact.

Again, if the animal twists or jumps while the arrow is in it (assuming a clean double lung passthru), it is reacting to either the sound of the shot or some movement the hunter made. Good camo and not removing too many branches can help mask movment. A quiet shot is helped by heavier arrows, and fingers release. I don' t care how quiet your bow is, releases are noisy critters. Not long ago, I was watching a guy shoot a new Legacy. VERY quiet bow. The only sound that really stood out was the metallic click of the release jaws snapping open.

Another possible product for Simms. Release silencers!