Shooting lockbows with low string friction

I've been wondering about prod angles lately, so I added a wedge at the front to reduce string contact as much as possible. This does seem to help with distance quite a bit, but some of my bolts started tailwagging. Previously I've never had such issues with these very bolts. I tried extending the bolt clip and applying more pressure to it, and it works, but is neither the most elegant nor the most reliable solution. Seems like different bolts need different combinations of clip strength and position.

I tried several clip profiles and again the same, it works but sort-of. I suspected the problem might be the clip itself and possibly its interaction with the string, so I tried shooting clipless, but still some bolts just wouldn't fly right.

While shooting without the clip, I tried tacking the bolt to the groove to stabilize it. I put some bits of clay at both ends of the groove, and noticed the string doesn't remove any excess that protrudes above the top plate. So I added more clay to the sides to test this further, and just like that, every time I shoot the string jumps right over it. I believe it can jump as high as 2mm, for a distance of at least 4cm, until it engages the top plate. 

To counter this, I filled the far end of the bolt groove with wax, as a flush bolt rest, removed all the clay, and suddenly everything just fell into place. Now I can shot with or without the clip, and there is simply zero problems again, like there is a much lower prod angle. Of all the things I've tried this simple raising of the bolt tip seems like the closest to perfect solution. I'd be interested to hear if others found different hacks to the same or similar problems, perhaps when shooting with rolling nut or snaplock mechanism.

I also put a slight concave semi-nock into one of the bolt ends. I'm not sure whether this helps or not, but I couldn't find any downsides. If anything it flies a bit further, but I might be subjective (didn't have the opportunity to fully test it yet). Also my flat bellied prod sprung a splinter some time ago so I had to repair it with hemp backing oops. I guess bare wooden prods were made with round section for a reason.

VERY interesting observations and solutions! Now I've got to try a few things myself!

Very interesting notes, I posted a question about my bolts wagging their tails a while back.  Will give try raising the tip and see what happens.  Thank you for posting.  Incidentally the string on my lockbows always seems to hop up in the way you describe, so much so that I stop the bolt groove an inch or more before the string slot to allow time for the string to move towards the table sufficiently to engage the bolt - I have even had one bow where the string rode along the bolt causing a dry fire. I filled in the first 3cm of the groove which almost entirely eliminated the issue but In this bow, my bridle bindings were also suspect and replacing them with a stronger binding reduced a tendency for the bow to rock.  Having said that, I also think that allowing the bow to move slightly reduces friction between string and table as the bow doesn't push down as heavily as it might with a very tight bridle...

Interesting. A useful observation. 
I have had bolts drawing streaks of cresting paint on bolt table in front of the lock. Even with a trackless roller-nut bow where the bolt is not supposed to be touching the tiller at all. 
So apparently there is to be expected violent vertical string movement in the early stages of acceleration.
   I have not paid attention to this earlier as it did not seem to hurt the accuracy, although my heavier bolts have often been slower than they should. Suggesting a possible cause of inneficiency.