In my earlier years working while going to college, I worked in a machine shop helping in retrofitting old gun boring lathes into trepanning lathes called trepanners. The old gun boring lathes were originally built by LeBlond Machine Tool for war time use in WWII for gun drilling, skiving, rifeling gun barrels up to 350mm. LeBlond built these machines in six sizes that I'm aware of and were specified by the size by numbers 1,2,3,4,5, and 7. Don't know why 6 was skipped, (maybe 6 is the devel's number?) but it was. Anyways, the number 4gsr was the machine size I used to help retrofit. LeBlond built these machines in lengths of up to 60 foot in length. The machines I worked on were built in lengths up to over 120 feet in length and would drill holes from both ends at the same time and put holes in steel bars up to 54 foot in length. That's where my handle originated from.