Did you purchase it new or used? There have been some instances of people buying used guns that have been dry fired and the nipples ruined. Take a good look at the nipples to see if they have been peened in. If not, there is a possibility that the hammer strike angle is wrong. If the angle the hammer strikes at is too large, you'll get inconsistent ignition. To test this, cap a nipple and put some grease on the face of the hammer. Then lower the hammer slowly onto the cap and let it rest. Now inspect the cap, is there grease all over the cap or is it a little half moon shape? If it's a half moon, your hammer strikes at too great an angle to give consistent ignition.