I posted this in the wrong thread earlier.
After reading your post, I too, did some more research since I was recommended a 340 spine. Per every arrow spine calculator that I have researched, it looks like my spine deflection should be much lower.
The Easton calculator seems to be the most confusing.
From the Easton website: (
https://eastonarchery.com/huntingshaftselector/)
1. Determine your correct arrow length per diagram above.
2. Determine correct peak bow weight (not holding weight) and draw length with the assistance of a qualified archery pro shop.
3. Determine the ATA (Archery Trade Association) rating velocity of your bow.
4. Factor variables to the “standard compound setup” to determine CALCULATED bow weight. For compounds the “standard setup” includes use of a release aid and a brace height greater than 6.5”. Deviations for the standard compound setup require factoring in EACH VARIABLE as follows:
A. Brace height lower than 6.5”- add 5 lbs to CALCULATED bow weight.
B. Finger release- add 5 lbs to CALCULATED bow weight. Add the total of actual PEAK bow weight and all CALCULATED bow weight adjustments to determine final calculated weight. For example, with a 60 lb peak bow with a 6” brace height, calculated bow weight will be 60+5 for a calculated 65 lb bow weight. Now, in the “Calculated Peak Bow Weight” chart, select the column under the ATA range for your specific bow and your point weight. Follow the column down to your CALCULATED bow weight. Then, follow the chart to the right until you reach the column with your correct arrow length, and note the group letter (A-M). This letter will represent the suggested arrow group for your selection.
I'm shooting a Mathews Vertix set at 70lbs and ATA rating velocity (or IBO) of 343 fps. So add 5lbs since it's over 340 IBO, which now = 75lbs
Also add another 5lbs since the brace height is less than 6.5", so add another 5lbs, which now =80lbs
Again, add another 5lbs since I'm using a finger release. That gets to 85lbs.
So going off of Easton's charts and their calculator, there isn't an arrow that fits the math.
Am I doing something wrong? If so, what am I screwing up? Either way, I have been shooting 340 Axis arrows and that is what I plan on flinging at an elk if I get the opportunity.