Take the gun back to the store. They will either fix it if they have a gunsmith there or tell you how to get it fixed free from T/C Inc. You should always test the trigger on a new rifle upon taking it out of the box & firing it with a couple of primers. If the trigger was stiff while still brand new (before you fired it with powder), then the store would of allowed you to exchange the rifle for another one.

Now you may be forced to pack the gun in your purchase box -- have it mailed to T/C & wait for it's return.