Results from spine-tuned arrows
This is related to the post where I described a spine tester that I built. To test the value of spine-tuned arrows, I fletched a dozen Gold Tip Hunters 7595 and shot them at various distances with 125 gr. 2-blade Magnus Stingers. I decided on these lower priced carbons, which are reputed to have poor spine consistency.
I asked for input on what an acceptable spine variance would be, and didn't get an answer yet, so I decided to test some of the arrows that had more variance than the others. I choose five arrows where the weakest and strongest sides were between .008 and .015 difference. I have no idea if this falls in a good or bad range, but I figured these were no better than average for a dozen GT hunters. Out of the dozen, there were 6 other arrows that measured more consistant than these and one that measured much worse.
After testing with the spine tester, I marked the weak side of each arrow and placed the cock fletch on that mark. I used 4" feathers attached with a helical clamp. Draw weight was 65 lbs out of a hybrid cam bow. Draw length was 28.5" and arrow length was 28.75". The bow was well-tuned and shooting field tips very well if I did my part. A whisker biscut was used as the rest. A mechanical release was used. I shot the 5 arrows with the Stingers attached, at broadhead targets set at 20, 40 and 60 yards. The arrows were shot one at a time and then marked. I wanted to determine group size and location without actually shooting a group. A total of 3 groups were shot at each distance and averaged to determine group size and location.
To start, no tuning adjustments were made and the sight was not adjusted. At 20 and 40 yards I could tell no difference in group location between these arrow and my field tipped arrows. The sight needed absolutely no adjustment and no tuning adjustments were made either. The group size at these distances was actually a bit smaller than my normal field tip group. It is likely I was just having a good day shooting, but all five arrows flew nicely into the group. Normally, I'd shoot a dozen, culling them down to the best 4 or 5 shooters in the bunch. I found it refreshing that none of these appears to need to be culled.
At 60 yards the group location was still right one, but it did widen to a bit more than normal. There was about a 15 mile per hour wind that may have been influencing them at this distance.
Overall, I was very impressed with how these cheap carbons flew when spine-tuned. This test was certainly not conclusive of anything, but it did give me reason for optimism. I'll be shooting these a lot over the next couple weeks (before the season opens), to try and determine if these were just better than normal arrows for a Gold Tip Hunter, or if the spine tester will prove to be very useful.