I believe Zep45 Dual Force is simply Zep45 with PTFE (Teflon) added. I haven't used it a great deal, but it seemed to work as good as regular Zep45. I have never used Zep45 Sidewinder, but doubt if it has any magical properties that would make it that much better.
You have been playing with this for less than two weeks. Some guys would have resorted to chisels, drills, and easy outs on day one. They might have also done permanent damage because of impatience too. This is a juncture where many old guns end up in the scrap box or get parted out. But I can recall some screws that resisted all efforts for weeks before finally moving. I had one of those notorious compensating screws on the action knuckle of a Lefever that wouldn't budge after using alternating heat, cold, vibration, tapping, etc. for a couple weeks. I finally doused it with several drops of that old Tasgon and wrapped the area in Saran Wrap to keep the penetrating oil from evaporating. I put it aside and moved on to other projects, and basically just forgot about it for about 6 months. When I finally got back to it, moderate torque on the screwdriver easily broke it free, and it took virtually no force to remove it. The threads were wet all the way down.
I'm saying that resorting to the chisel this soon may be rushing things if you don't need to use the gun for bird hunting next month. If you gall and tear the threads in the action, you may end up asking us how to make and install an oversize bushing. And as a last resort, before I used a chisel, I might think about the neat trick of welding a hex nut onto the bushing with a MIG welder. You use a nut with an I.D. somewhat smaller than the O.D. of the bushing, carefully center it, and weld the I.D. of the nut solid to the face of the bushing, or broken bolt, stud, etc. The intense welding heat breaks the bond of the rust, and after it cools, the hex flats allow you to turn it out with a wrench. More penetrating oil is advised because the welding will burn out any trace of lubrication. It is a last resort, and will require a new firing pin bushing if it works. the bushings are not perfectly perpendicular to the breech face, and the new one will need to be fitted and dressed.
