Yellow jackets cut nice holes.
Aside from that, are you shooting purchased targets or targets you printed out yourself? When I print targets at work, I print one copy out and then photocopy a bunch of that target onto coloured construction paper that I buy in a pad at Walmart. Humidity can really affect how your targets tear. Try to keep them dry and they'll cut holes. Some air gun guys put their targets in teh over for a while at low heat to get nice clean holes.