Jent has a good idea, if you can make it to Harrisburg. My two main points were that I doubt if the ammo has anything to do with your gun being hard to open. The other point is to have the gun thoroughly checked out. Based on my experience, it seems more likely to be a bent or broken firing pin that won't retract when the primer slides by it when you start to open the gun. Remember, these guns do not have springs to retract the firing pin. Only the camming action of the shell lifting up pushes the firing pin back into the breach face. The experienced Smith shooters at Harrisburg could certainly sort it out.