I've posted this before but here it is again.
So around 14 gr/i might be optimum. But in the past few years I've many good tough handles in the 10-12 gr/i range. If I'm in the 5-20 range then I let grain orientation and lack of runout be the deciding factors.
I looked at that data and wrote this about it in an earlier thread:
Taking a closer look, however, it doesn't seem so cut-and-dried. From the graphs, it's clear that for hickory with 5 to 20 growth rings per inch, the "Strength At Maximum Load" is around 11,000 (the units aren't labelled), but for between 20 - 35 rings per inch, the Strength doesn't drop below 10,000. So that's only about a 10% reduction in strength if you have 35 rings per inch, compared to the ideal. Is this enough reason (by itself) to reject a handle, or will it still be strong enough (if there's no problem with grain runout, etc.)?
Looking at the graph of shock-resisting ability ("Bending Work to Maximum Load"), 5 - 11 rings per inch gives the highest values, while there's a plateau between 14 - 38 rings with roughly the same values.
Based on this data, it looks like the best hickory would have 5 rings per inch. Increasing from 5 to 11 rings per inch would slightly increase the strength (less than 5% increase), but the shock-resisting ability would
decrease by 17% (or so). Between 11 - 35 rings per inch, the shock-resisting ability is about the same, while strength drops slightly as the number of rings increases.
So my takeaway from this data is that I would not reject a handle solely on the basis of rings per inch, unless it was over 35 (or so) rings. Especially since
"in the case of normal growth upon dry situations... the slow-growing material may be strong and tough". In other words, the slow-growing, many-ringed hickory could be stronger and tougher than shown in the graphs.
from
https://www.bladeforums.com/threads/hickory-rings-per-inch-heartwood-vs-sapwood-etc.1222258/