According to the Easton chart, I should use xx75 1916 for my 40# longbow. I've got a chance to get a good deal on some 1914's which are rated for lower draw weight. Will the 1914's work for general backyard target shooting or should I stick with the 1916's? I'm shooting a 28" arrow.

Easton charts are stiff you should do well with the lesser spinned arrow

In the How To section on the main page is an aluminum chart,check that one out and see if it is different than the Easton chart you are using.