Lots of great info.I apprecaite all the input!!

Now I guess I have to shoot my crossbow through a chronagraph to know how fast it shoots????Then I can set the speed ring??? or canI use a trial and error method by zeroing it at 20yds then shoot at 30 and 40 using the triangles,then setting the speed ring at different settings, and shoot again until I'm on at 20, 30 and 40yds????
I suspect than the speed ring isn't exact by FPS as each bow will vary depending on arrow, fletching and broadhead