Yea, I feel you on the all different readings ordeal lol. I also saw the .0045 Mod Resistance, but I was told that was for the Brass Version 510. Not saying that it's not the same as the SS version - but you never know.
If you're looking for a definite answer, you can write to Bob (he's here on the forums) and order the tool I was referring to. I'lol post my results when it arrives, but from what I understand, the mod resistance can vary from device to device (clearly that's at least somewhat true, if someone came up with th value 0.022 lol.
Basically, you screw this tool into the 510 as if it were an atty, and you set your mod resistance to 0. Then you open the atty analyzer in Escribe and fire your mod (hope I'm not missing a step here) and it'll display your Mod Resistance. And you'd use 80% of the value that's shown.
If you want to order one, his email is bob.bmb.lewis03@gmail.com. Nice guy, he had mine shipped out the next day for $10 including shipping. I think it'll be a nice tool to have around. Probably should have bought more to use as stocking stuffers lol!