Ken is right, my Harpoon Catoed on a Pro38, but it was a 4 grain and was due to a problem with the reloads themselves that were manufactured between July and December of 2001. Fortunately, Cesaroni gave me the entire scoop, way to go for them and I appreciated their honesty! In addition, I received a new casing and two reloads for my trouble, the second reload was to cover hazmat. Another plus for their customer service. Moreover, the damage to the Harpoon was minor as the motor casing traveled straight through the rocket, so it has since been repaired and flown again a number of times on more Pro38 4 grains.
I thought I had mentioned this before, but realized it was in a different private forum, so I will post it here. The Cesaroni Pro38 motors have an ignitor bead installed at the top of the motor grain, which is why it only requires an ematch to ignite. Some people I have heard place ignitors in their Aerotech motors half way up to try to get a more even burn. I don't know how effective this method is as I have not tried it and will stick to the mfgr's suggestion of running the ignitor up to the top. However, since the Pro38 motors require ignition of this ignitor bead, the ematch must be run to the top where the bead resides in order to light.
Also note, that since Pro38 uses an ignitor bead, only e-matches should be used to light the motor. A regular ignitor can cause an "overheat" condition in the motor, possible resulting in a cato. This is obviously proven with even the simplest ignitors, a larger ematch. It is undoubtedly overheating the smaller grain loads, resulting in a Cato. The larger grains tend to work fine with the larger ematches. So if you have to use another ignitor, stick with only ematches. Sure wish Ceseroni would start selling them on the side as I have had a few pop without ignition.
Just an FYI,
Carl