One Shot Wonder

I got the bow mount all finished and tested the clamped up bow on the tiller, it was fine and drew to 16" inches with no problem, I briefly flashed it to 18 inches and felt confident that it would be fine,
I got the mount fitted to the stock and plucked up courage for a test shot, I used a bolt which is usually shot from my bow pistol, my heavier bolts are fletched with 2 flights, are larger diameter and wouldn't fit correctly.
The good news was that the trigger held fine and the safety catch worked. The shot seemed fast, but the bow string went over center and one limb smashed. I can't actually be certain how it failed, maybe the shock (or vibration) broke the limb which then allowed the string to go over the top, or maybe the string stretched enough to go up a tad and over centre. If I'd had string bridges or grooves on the belly to catch the string, or maybe buffers like most modern crossbows and compounds have it would have been ok.
The limb failed at the patch, which is predictable as the patch is ok in compression but has no strength in tension if the bow goes past it's unstrung state and flexes the wrong way.

It would be easy to think it's a major failure, but in fact much of the work hasn't been wasted. I still have the form for the bow and the bow mounting, I also now have good dimension for the prod and confidence that it will take the draw length.
Onwards and upwards... with hindsight I'd have fitted string buffers/catchers, but one has to take that test shot at some point and maybe I was just too impatient, although if I'd used a heavy bolt, I could have got lured into a false sense of security and simply had the failure later.
The big shame is that I didn't shoot it through the chrono'.
I may try and mend that limb just so I can do more tests.