I'd say your doing great, Results on paper are the final result. No matter the method you use on truing the bolt, you can check your work pretty easily. After you clean up the rear of the lugs, take a clean up cut off the front of the lugs too.
When all done, simply put your receiver in a vise vertically with the bolt in a closed position (firing pin assembly removed). Pop a measurement with your depth mike from the square receiver face to the front of each lug. If your are spot on, or within a few tenths with the depth mike on the face of each lug, I would say you are more than good. If not, either your receiver integral lugs, bolt lugs or receiver face is out.
Lets face it, anyone with any real experience in a true machine shop with capabilities to work in tenths and millionths knows the equipment needed and how cycles in between heating and cooling the building alone can affect any metal and measuring. Food for thought.....
Romicron boring heads can hold seventy or so millionths, a finger print is roughly fifty millionths thick, and can cause problems while fitting spindle bearings.
Crystal Lake Grinders can be ordered with five millionths run out on its work head, which is absolutely amazing.
Monarch 10EE lathes have been factory tested (at one time, don't know if that is still true) to hold thirty millionths on a few inches of length.
Gage Blocks can be calibrated into a few millionths.
I believe new Sunnen Hones are guaranteed to hold fifty millionths.
Remember a healthy human hair roughly .003 thick
Have fun!
When all done, simply put your receiver in a vise vertically with the bolt in a closed position (firing pin assembly removed). Pop a measurement with your depth mike from the square receiver face to the front of each lug. If your are spot on, or within a few tenths with the depth mike on the face of each lug, I would say you are more than good. If not, either your receiver integral lugs, bolt lugs or receiver face is out.
Lets face it, anyone with any real experience in a true machine shop with capabilities to work in tenths and millionths knows the equipment needed and how cycles in between heating and cooling the building alone can affect any metal and measuring. Food for thought.....
Romicron boring heads can hold seventy or so millionths, a finger print is roughly fifty millionths thick, and can cause problems while fitting spindle bearings.
Crystal Lake Grinders can be ordered with five millionths run out on its work head, which is absolutely amazing.
Monarch 10EE lathes have been factory tested (at one time, don't know if that is still true) to hold thirty millionths on a few inches of length.
Gage Blocks can be calibrated into a few millionths.
I believe new Sunnen Hones are guaranteed to hold fifty millionths.
Remember a healthy human hair roughly .003 thick
Have fun!
