Hey DC,
That's the loop style I've made on every single string I've laid up, since I started making bows. It's like a simple snare slip knot, that tightens onto itself, when pulled. Truth is, I saw it on a youtube video search on string making. I believe it was a fella, sitting around a campsite, making a whitewood bow, and demonstrating a simple string making technique. I did it, it worked well, and I stuck with it.
One thing I like is how that loop style makes it impossible for the string to slip off to one side, no matter the nock style.
I twist my my looped end tighter than that, actually reverse wrapping about six inches out to start, before taking the looped end off the nail, and threading my unfinished string through the loop. Then I hang the threaded loop end back on the nail, and finish reverse wrapping the string.
Another bonus is, if you make a wide, flat-limbed primitive bow, that has wide limbs out to the tips, this style loop does not require a string with longer than average loops, to let the string slide far enough up that wide limb, so the bow can relax completely when unstrung. Because this loop will open infinitely large, and then tighten-down firmly onto the tiniest of pin nocks.
Just thought I'd chime in, since I've had good luck with it.
*My bows only range in weight up to the mid-60's, so I can't attest to those warbow weights.
–John
