XS,
Interesting.When you say "indexing pin", do you mean the pin that fits into the indexing holes in an Atlas lath's bull gear ? Do you use a milling attachment to clamp the barrel, in place of the compound slide or is it rigged some way to the tool post? If you index on the bull gear, is there some reason not to cut 4 or even 3 grooves, or was it personal preference? Is there a handle on the threaded rod to pull it by hand, or do you pull it under power some way? It seems like we have pretty similar interests( I guess so, or we wouldn't be on the same forum).
Mike