When your shooting with pennies for ammo start with close targets and shoot gently to get the feel of how the penny reacts leaving the pouch. Better results are obtained soft shooting as viewed in the video. Also tweak the pouch upward a bit and only have the penny just snugg in the pouch. Also the pouch must be turned on its side before the release. Results can be good if kept within about 30 feet.
http://youtu.be/G9VJcmvrLww