Spliced billets for a bendy handled bow.

[DC]

Maybe think of the glue line as a crack. With a horizontal splice the glue line is across the back, with a vertical slice the glue line is more lengthwise.

For sure, I follow what Mike is saying about a  "crack across the back".  And it is sort of natural to "feel" better about a vertical finger joint than a horizontal joint. Is this inclination based on experience or suspicion?

But going back to what was mentioned earlier.

The point of the "V" popped out.

So if the break starts on the surface, why would a point of a "V" act much different from a feathered edge cross ways?, as long as the taper and glue area was sufficient. We have seen vertical finger joints work and some that have failed, but I have yet to see a reported failure of a horizontal joint, although the orientation works in applications like sailboat masts etc. A patch or short cover lam used to cover a "W" splice has a cross ways glue line at the ends, and it's at the surface where stress is highest.

Just a gut feeling on my part. You'll have to try a couple.

[Sagebrush]

My neighbor is a newish bowyer and accidentally did this experiment last week.  He put together a beautiful splice. Upon stringing it and beginning to tiller it blew up in his hand.  I almost had to suture his palm (at 82 he was too tough for that:).  Wear a leather glove and post your results.