Usually somehow I manage to loosen them. This one has got me. I ahave an older waffle top 336 and the trigger pull is a bit too light. I have worked over sears and tumblers in muzzle loaders and am pretty sure I could stiffen it up a bit. I moved the spring into another notch and it helped some, but its just too light. Problem is that I cannot get the hammer screw out. I think someone may have used some kind of thread lock on the screw. I first tried a screw driver using the super slim blades needed for the slim slots they use in gun screws. The blade bent but no loosening. I have tried using an impact driver with the idea that I am going to have to replace the darn thing anyway. The impact driver blade bent but no loosening. I now have two options. One is to apply heat and see if I can get it to pop. Not crazy about that although I could apply a heat sink above it. The other is to carefully drill it out as I have ot replace it anyway. Any ideas out there? I removed the spring so there is no pressure.
DEP