Ontarget2 from pinwheel software predicts optimal spine for your setup. It has database of most bow setups (by brands and models) and arrow setups. Just put in your bow setup and it will predict the best spine. You can play with changing your draw weight or arrow length or broadhead/field point weight to get really tight on the optimal spine. There is a free trial version you can use to figure out your best setup and it is relatively inexpensive if you decide to buy it. Much less expensive than trying 340's...and finding out they are too weak spined, then buying 300's...and finding out they are perfect at your arrow length for broadheads, but a little short for field tips which would shoot with the same dynamic spine as your broadhead if they were 2 inches longer...which would allow you to shoot the appropriately spined arrow at your center shot rather than moving your sight to "tune" your broadheads to hit where your field tips on the same sized arrows hit and realize you can't get them any closer than 5 inches. The free trial is 4 days for the shaft selector, and 10 days for the combination (which also has the shaft selector), so you can essentially take 14 days to play around and optimize your spine for both broadheads and field tips. I'm still working on the trial version, but will probably buy it. If you buy the tapes and charts, it will also help set up your sight pins. That part is a little complicated. ~$13 for shaft selector, $22 for tapes and charts, and $28 for the combination which also has some other neat features, like the simulations. Wish they would pay me for the free advertising
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BTW...if I had used the "charts" to choose my spine, I would have been way underspined.
