We are making head way on the VG1-5. There are a lot of small steps that take a great deal of time to accomplish. In this case it is the two hole on the bolt that lock it into the upper receiver and hold the firing pin in place.
A quick video.
This how the bolts looked as they came back from heat treat. These are the two test bolts that were sent along to test the heat treat specs. You can see the marks on them to differentiate them from the actual rifle bolts.
This is an actual bolt after cleaning.
The two holes that were undersized after heat treat. These bolts are made of 8620 and case hardened to .020 deep.
The series of reamers that we used to try and open the holes.
A new lap as received from the supply house.
The adjustable lapping tool
Some of the laps that we went through bring the holes up to the proper size.
The gauge pins used to test for proper size.
It actually took a couple of weeks off and on to finish this step. The reason for this was testing the different processes necessary to provide a correct product.
CRAP! Reminds me of the time I took on the task of opening up the holes in 2 sets of M16 fire control parts to the large pin hole size. 2 Carbide reamers and lapping after wearing out those reamers.
Pete
Isnt it possible to coat the inside of holes prior to caseh. with some compound to prevent the haedening of them and thus this swelling?