Make sure when you warm the cartridges up to ambient temperature before using. When working cattle it would be a good idea to store the open packet in a dry cooler in between and make sure the foil is closed tight in between usage. In humid weather the pellets will want to take on moisture which causes the gun to jam.
After use, make sure it's sealed tightly and stored in the refrigerator. Don't put them in a zip lock bag because plastic likes to take on moisture and don't store them in the freezer.