I have had the Barnett Quad 400 for several years and killed a number of deer with it. This year I only had a few days to hunt and I shot a spike with it at about 30 yards.
Even though it is fairly noisy it is so fast (345 fps) that before the deer reacts the arrow has passed through him. I forget exactly how many deer I have killed with it but the story has always been the same. The deer looks startled and the bolt is sticking in the ground already.

It is very accurate with field tips but when I shoot broad heads it is way off (even with mechanicals that claim same as field tips) At Academy they told me to use the Barnett expandable so I did. It's better but way off from the field tips. I just kind of zeroed it in between 20 & 30 yards. It is probably off an inch or so at 20 yards and maybe just a little more at 30 yards.
I tried all of the tricks I know including new bolts and adjusting the tip in relation to the vanes but that's the best I can get. All that being said it kills the deer just as dead!!!!
I have never in my 64 years seen a deer bleed out so juickly as the spike I shot this year! It almost seemed like I saw a hole all the way through him!