Use LubriPlate- the same white lithium stuff you put on your Garand.
You DO have a Garand, don't you?????
But really, a dab of grease does the trick, and doesn't hurt anything that I have seen... through a half-dozen HK pistols that I installed LEM kits in using the method. I did my FDE HK45C yesterday, in fact. Like Todd said, the big trick is holding the frame just so to get those three parts onto the hammer axle in the right orientation.
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