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Tuesday, March 27, 2012

Dealing with Arrow Variance

This is a technical article and to fully understand the message, you will need to follow along. On Saturday, Kodabow was shooting with an outdoor writer. We numbered three brand new arrows - #1 , #2 and #3 and stepped back to 40 yards. The first shot sequence is shown as the orange dots. Arrow #1 was 2 1/2 inches high and left. Arrows #2 and #3 (both orange dots) were about 3/4" apart just right of the bullseye. The second shot sequence (blue dots) nearly replicated the first sequence. There was a clear pattern being defined. Arrow #1 was flying high and left but the other two arrows were grouping less than 1" apart. In fact, looking at the group made by the two consecutive shots of arrow #2, the arrow #2 group was less than 1/2" --- the same for the two shots of arrow #3. Individual arrows were grouping within 1/2" at 40 yards so the crossbow was shooting very well. For the 3rd shot cycle, we made one change. We rotated Arrow #1 so that the cock feather was now at 2 o'clock vs. the typical 6 o'clock position. The resulting shot is the yellow dot. By changing the orientation of the arrow #1 on the rail, arrow #1 joined the rest of the group. Note that when arrows #2 and #3 were fired in the third shot sequence (green dots), they grouped as expected and were still shooting 1/2" groups on an individual basis.
Here are the lessons learned.
#1 Number your arrows on the vanes with a felt tip marker. This allows you, the shooter, to make sense of target results.
#2 Shoot a few sequences until you see a pattern emerge. Prior to shooting with the writer, he was told to expect "zero crossbow variance" with the Kodabow crossbow shot to shot ..... and when we pull the trigger precisely, we will have "zero shooter variance." The pattern that we will likely see emerge will be attributed to arrow variance.
#3 Correct for arrow variance. Kodabow uses flat nock arrows. A shooter has 3 options for placing an arrow on the Kodabow rail. That is the cock vane can be placed, down at 6 o'clock , right at 2'oclock or left at 10 o'clock. (This is an advantage of flat nock Kodabow arrows.) A shooter can optimize results by trial and error and tighten groupings by also keeping track of arrow placement and then marking the vanes accordingly. We could have easily culled arrow #1 from the pack and labeled it a bad arrow and tossed it aside but a little analysis went a long way.
Why is this happening?
Arrows will have slight variance in spine within the same arrow --- that is, one side of the arrow might be a little heavier than the other. This causes the arrow to fly slightly up/down/right or left. Some shooters go real deep into the matter and float their bare arrow carbon shafts in water and after a few moments, the carbon shaft orients heavy side down and light side up. They will mark the arrow and then fletch the arrow with the cock feather on the heavy spot expecting more consistency when all the arrows are built in that manner. We just shoot the arrows and get at the same result --- works better for us because we are dealing with actual shooting results. By the way, if you are interested in seeing how consistent your crossbow is shooting, use one single arrow (to eliminate arrow variance) and look for very tight groups.
The final result. Outdoor writers are very discriminating consumers. They see lots of gear and in some cases, get plenty of free stuff. After shooting Kodabow with us, this particular writer promptly said, "I need to buy a Kodabow" and placed an order for a Koda-Express 185. We hope this helps you on the range. Be safe.
The Kodabow Team

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