I used \"ruger\" style extractors and set the gap to .055\" which is what others recommended. I haven\'t fit the firing pins yet, so can\'t say what I will have when trying to extract fired shells, but with un-fired shells, it cycles them through and looks to extract well.
I also measured a few other .22 rifles I have and they were around the .055\".
I agree that the .063 recommended on the RGG prints seems excessive.