Calling Arrow Experts (Again)

FirstFreedom · December 4, 2007, 10:42 PM

This is another question about arrow flex, if anyone can help.

My Liberty Bow has a bit of an overdraw (set back W. Biscuit), so I am going to cut down 6 arrows, from 28-29" range where they are now, down to 24.5" (actually 25.0" with the nock included, but not tip). Anyway, assume a 70 lb. compound draw weight.... my question is which of these two arrow types which I have will likely be the most correctly spined for this bow when cut to this length? One constant will be fletching, if that matters - they will all have 2" Blazer vanes regardless:

1. First (Primary) Question: With 100 grain points, which of these two arrows are most likely to have the correct flex for the Liberty bow set at70 lbs, with arrows @ 24.5" (25" with nock):
(a) Carbon Express Thunderstorm SE, .280" diam, approx. 6.9-7.0 GPI, flex rating= Unknown (but more than the Epics)
(b) Easton Epic ST, .280" diam, 8.7 GPI, flex rating=.400 (easton system)

2. Secondary Question: (Would your answer change with a heavier point, providing more flex)? With 125 grain points, which of these two arrows are most likely to have the correct flex for the Liberty bow set at 70 lbs, with arrows @ 24.5" (25" with nock):
(a) Carbon Express Thunderstorm SE, .280" diam, approx. 6.9-7.0 GPI, flex rating= Unknown (but more than the Epics)
(b) Easton Epic ST, .280" diam, 8.7 GPI, flex rating=.400 (easton system)

It's possible that the answer is the "flexier" Thunderstorm SEs with the 100 gr points, but instead, the less flexy Epics with a heavier 125 grainer. The Thunderstorm SEs are definitely too much flex for the bow with 27-29" arrows, but they get stiffer the shorter you go, of course....

I'm leaning toward cutting down and using the Thunderstorm SEs, but please let me know if you think I'm making a mistake (if they will STILL be too flexy @ the shorter length).

Thanks!

If you don't know, don't sweat it - I'll just copy & paste and re-post over on the archery forums if nobody swings by here....

FirstFreedom · December 4, 2007, 11:19 PM

Nevermind; decided to run with the Easton Epics, for a variety of reasons, but mostly because more weight=better penetration on game, and I'm 90% sure that the Epics won't end up TOO stiff when cut down.

http://www.bowsports.com/acatalog/est-04-chart1.gif

Oops, nope; after consulting that chart, looks like I need either a T8 or T9 arrow, and that means much more flexy than a .400 - I need a .500+ flex, so back to the T-storm SEs.

jrothWA · December 4, 2007, 11:44 PM

set-up a video camera behind you when releasing the arrows. that should give you a visual on what occurring and point you in the right direction.
Have a recurve that I haven't used lately, but the wall thickness, point selection and length all affected flight.
Used 125 FP for practice off-season, month before swapped to 145 Bear broadheads, here the heavier weight countered the planing action of the broadhead.

December 4, 2007, 10:42 PM	#1
FirstFreedom Junior member Join Date: May 31, 2004 Location: The Toll Road State, U.S.A. Posts: 12,451	Calling Arrow Experts (Again) This is another question about arrow flex, if anyone can help. My Liberty Bow has a bit of an overdraw (set back W. Biscuit), so I am going to cut down 6 arrows, from 28-29" range where they are now, down to 24.5" (actually 25.0" with the nock included, but not tip). Anyway, assume a 70 lb. compound draw weight.... my question is which of these two arrow types which I have will likely be the most correctly spined for this bow when cut to this length? One constant will be fletching, if that matters - they will all have 2" Blazer vanes regardless: 1. First (Primary) Question: With 100 grain points, which of these two arrows are most likely to have the correct flex for the Liberty bow set at70 lbs, with arrows @ 24.5" (25" with nock): (a) Carbon Express Thunderstorm SE, .280" diam, approx. 6.9-7.0 GPI, flex rating= Unknown (but more than the Epics) (b) Easton Epic ST, .280" diam, 8.7 GPI, flex rating=.400 (easton system) 2. Secondary Question: (Would your answer change with a heavier point, providing more flex)? With 125 grain points, which of these two arrows are most likely to have the correct flex for the Liberty bow set at 70 lbs, with arrows @ 24.5" (25" with nock): (a) Carbon Express Thunderstorm SE, .280" diam, approx. 6.9-7.0 GPI, flex rating= Unknown (but more than the Epics) (b) Easton Epic ST, .280" diam, 8.7 GPI, flex rating=.400 (easton system) It's possible that the answer is the "flexier" Thunderstorm SEs with the 100 gr points, but instead, the less flexy Epics with a heavier 125 grainer. The Thunderstorm SEs are definitely too much flex for the bow with 27-29" arrows, but they get stiffer the shorter you go, of course.... I'm leaning toward cutting down and using the Thunderstorm SEs, but please let me know if you think I'm making a mistake (if they will STILL be too flexy @ the shorter length). Thanks! If you don't know, don't sweat it - I'll just copy & paste and re-post over on the archery forums if nobody swings by here.... Last edited by FirstFreedom; December 4, 2007 at 11:33 PM.

December 4, 2007, 11:44 PM	#3
jrothWA Senior Member Join Date: November 11, 2006 Posts: 2,519	If you can... set-up a video camera behind you when releasing the arrows. that should give you a visual on what occurring and point you in the right direction. Have a recurve that I haven't used lately, but the wall thickness, point selection and length all affected flight. Used 125 FP for practice off-season, month before swapped to 145 Bear broadheads, here the heavier weight countered the planing action of the broadhead.

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December 4, 2007, 11:19 PM	#2
FirstFreedom Junior member Join Date: May 31, 2004 Location: The Toll Road State, U.S.A. Posts: 12,451	Nevermind; decided to run with the Easton Epics, for a variety of reasons, but mostly because more weight=better penetration on game, and I'm 90% sure that the Epics won't end up TOO stiff when cut down. http://www.bowsports.com/acatalog/est-04-chart1.gif Oops, nope; after consulting that chart, looks like I need either a T8 or T9 arrow, and that means much more flexy than a .400 - I need a .500+ flex, so back to the T-storm SEs.