George, if I am correct stringwalking was used in ‘67 in field competition - high anchor was known already. How they fared for long shots? Once I am at point on it becomes a gap aiming method.
Draven, yes...string walking was prevalent in field and target competition well back in time. The high anchor as shown was used by a lot of bowhunters back then as well, and that's what I refer to. Most of the barebow, stringwalkers, went to the split hold out at long distance. It varied by archer of course. When the PSAA initiated the bowhunter barebow round, then you had to have just one anchor and the index finger had to touch the nock. In that round, string walking was not allowed but most guys still shot three under and worked out the long gap.
Jim....yes, that is gun barrelling in the vernacular of the time. I've even seen guys gun-barrel split finger as well for short targets.
A high anchor will shorten your point on distance, however i have found it very difficult to get into my back muscles with an anchor higher than middle finger near corner of mouth. I use a combination of things to get my point on where i want it. If your form accommodates a high anchor, go for it.
High anchor, or “gun barreling “ weather split finger or three under was popular with hunters as well as target shooters when I started out back when. I knew guys that could use different anchors for different distances rather than string walk. I guess if you practice enough lots of methods could work.