I would agree with overspined that one loop looks way oversized.  Is it coming off the upper limbs nock? 

What is the brace height of the bow?  Is it within the bowyer's recommended range?  Sometimes, if the brace height is too low, the string will come off during the shot.

--Mike

Looks like mighty big string loops on that string for a longbow.
I think your problem is the string and not the bow.

Maybe but none of my bows have the loop notches that look so poorly done.

Picture bow6 shows the nocks are not cut at all evenly.  Right side being way higher than the left.

It's an optical allusion of having crooked nocks. I have already spoke with the bow owner and without a shadow of a doubt, his brace height was considerably too low when the strings came off and when the string hit the back of his wrist.  This is a common mistake with the forward handle bows although I have never ever had anyone tell me that they had issues with their string coming off.

Now I have been wrong before, just not lately! 

This is one of my builds, and while I'm sure it's not perfect, I know what it isn't.
BIgJim

One of the problems in trying to help out folks with various problems is that we seldom know the OPs experience level and almost never have all the facts/information to offer definitive answers.  But that doesn't stop us from speculating, filling in the blanks and doing the best we can. 

Thanks for straightening it out Big Jim.