I'm with broncbob,you more than likely got oil in the chamber and this will cause high pressure.You have to dry patch the chamber when you put anything that is similar to oil in the chamber.Clean the gun and dont put any oil in the bore unless you wont be shooting for awhile. But before you go out make sure that chamber is dry or the case upon ignition cant grip the chamber walls like it is supposed too. If the oil was present you will get wild pressure spikes.