# Arrow weight variance - how much is a problem?



## Honker-Konker (May 10, 2012)

I like my arrows to be within 5gr of each other and have them all within 3gr with this batch of arrows I fletched up. I've had some closer to a 10gr difference before but i couldn't tell any difference in my shooting ability.


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## lksseven (Mar 21, 2010)

I should add more info - the arrows in question are for Olympic style recurve target.

(thanks for your input, Honker)


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## Destroyer (Sep 11, 2009)

Differences in spine make a bigger difference imo but I like to have mine within 2 grains.


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## Bean Burrito (Apr 20, 2011)

I weight matched all mine with a 0.01 gram (0.15 grain) scale, so they're all pretty dead on, half a grain or so. Why buy high end weight matched shafts and be lenient on your weight variances


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## caspian (Jan 13, 2009)

I can generally get mine to within a 0.2gn variance with simple weight matching with a $20 eBay scale. it seems silly to spend hundred of dollars on a set and then disregard best-effort matching.


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## limbwalker (Sep 26, 2003)

Grouping is affected by 1) spine consistency, 2) weight variation (which also affects spine) and 3) straightness, in that order.


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## lksseven (Mar 21, 2010)

John,

So, I can (have) weigh my arrows, and group them that way. How can I (can I?) determine spine consistency 'up front' (as opposed to keeping meticulous notes over a thousand shots and identifying similar spine consistencies via linking similar scoring patterns)? Also, how to determine 'straightness'?


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## Bean Burrito (Apr 20, 2011)

Spine consistency can be done on a roller jig with weights and a dial indicator. Straightness is the same, except instead of measuring deflection you measure runout when the arrow is rotated. John may be able to enlighten you further, but bareshafts at longer distances can weed out any arrows playing funny buggers (provided you shoot well enough)


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## limbwalker (Sep 26, 2003)

Bean has it correct. If you have the equipment...

If not, then strip all the fletchings and shoot the entire batch of arrows bare, at the longest distance you're comfortable shooting bare shafts at, and look for fliers. If an arrow consistently won't group, rotate the nock and try again. If it still won't, mark it and only use it for practice. This is what I do with all new batches of arrows I get. Fortunately, since I switched to CX arrows, I get very few, if any, fliers. That wasn't the case with A/C arrows - there were always a few that wouldn't group with the rest, but once you know which ones they are, it's not that big of a deal. I just like getting 12 useable arrows in each dozen...

After you select them by bare shaft grouping, then fletch them and do the same again, keeping good notes.

I am not that scientific about my process because I have enough details to keep track of in my life already. So I just keep track of how many points each arrow "earns" over the course of many practice sessions, and the ones that score the most points, get the highest place in my quiver. Pretty simple really.

John


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## Bean Burrito (Apr 20, 2011)

limbwalker said:


> Fortunately, since I switched to CX arrows, I get very few, if any, fliers. That wasn't the case with A/C arrows - there were always a few that wouldn't group with the rest, but once you know which ones they are, it's not that big of a deal. I just like getting 12 useable arrows in each dozen...


Not doubting you at all, but I'm curious if you have any ideas as to why this is. Spine/straightness/weight tolerances are similar, and in theory the A/C arrows should be more consistent as it is far easier to build a consistent aluminium arrow (or core) than carbon. I checked all my new arrows and they came up well within the guaranteed specs. Perhaps an all carbon arrow has a quicker recovery out of the bow which leads to better performance with bareshafts?


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## limbwalker (Sep 26, 2003)

> Perhaps an all carbon arrow has a quicker recovery out of the bow which leads to better performance with bareshafts?


 Perhaps. 

All I know is what I see on the target. Never had an A/C shaft do this at 70M before:


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## calbowdude (Feb 13, 2005)

My own SWAG theory is that because there are a lot of different steps involved in an AC arrow: pultruding the aluminium, bonding/winding carbon onto the aluminium, creating the barreling effect on ACE/X10 while at the same time ensuring the carbon is evenly distributed around the alu core, and probably about a hundred other steps I don't know about. I suspect Nanos/McKinney's are a couple of steps simpler to manufacture.


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## hwjchan (Oct 24, 2011)

limbwalker said:


> So I just keep track of how many points each arrow "earns" over the course of many practice sessions, and the ones that score the most points, get the highest place in my quiver.


Haha, I like it!



limbwalker said:


> All I know is what I see on the target. Never had an A/C shaft do this at 70M before:


:jeez:


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## Bean Burrito (Apr 20, 2011)

calbowdude said:


> My own SWAG theory is that because there are a lot of different steps involved in an AC arrow: pultruding the aluminium, bonding/winding carbon onto the aluminium, creating the barreling effect on ACE/X10 while at the same time ensuring the carbon is evenly distributed around the alu core, and probably about a hundred other steps I don't know about. I suspect Nanos/McKinney's are a couple of steps simpler to manufacture.


The aluminium core is an advantage in terms of manufacturing simplicity. It is much easier to straighten an aluminium tube or make it consistent to a very exact weight. The barrelling would make manufacturing a bit more difficult, but the end product is still made to very good tolerances.

On paper (and in measurements) the X10 and nano are very comparable. With my dozen Eastons tolerances were better than the guarantee. It's only when you get to the target (and this may not be the same for every archer) that one will seem better than the other. Like I said, my theory is an all carbon shaft will have a more rapid recovery when not used with fletches (compared to the A/C shaft). Chaos theory dictates that any instability in the arrow in the first small section of flight (as it stabilises) will have the greatest effect. Even a very slightly quicker recovery could lead to a big difference on the target at 70m.

IMO, when the fletches are on that advantage is pretty much negated, and will have a much smaller impact.

Each shaft has it's advantages. I like the weight of X10's, while some archers will need a lighter all carbon shaft. Barrelling is an excellent feature for recurves. Nano's have excellent durability. X10's slightly less wind drift. 

All that said, the effectiveness of the X10 can't be disputed.


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## Destroyer (Sep 11, 2009)

limbwalker said:


> Grouping is affected by 1) spine consistency, 2) weight variation (which also affects spine) and 3) straightness, in that order.


I would put straightness as no.2, affects spine too.


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## cc46 (Jan 22, 2005)

A while back here on AT there was a discussion similar to this. 
What I remeber was that, ~3 grains difference in arrow weight equated to ~1 fsp difference in speed, and if that was 200 fps vs 199 fps then the heavier arrow would drop about 2 1/2" more at 70ms. Or one ring lower. So 10 grains difference would be 3 rings lower at 70m on a 122cm face. 

Slower arrows at say 180 fps the drop is more pronounced as 1 fps diff on 180 fps is greater that 1 fps on 200. 
And for faster componds arrows the drop is less significant because 1 fps on 280 fps is smaller.

So depending on your skill level you may or may not notice this.


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## ccwilder3 (Sep 13, 2003)

I just went out and did a little experiment. I took the three arrow which were the closest in weight (all within .2 gr). I shot them with 65 gr tips and 75 gr tips at 70 meters. 15 shots with each weight. All arrow were measured from the top of an 80 cm target to the top of the arrow to the nearest 1/8 inch. I found the median of each set and eliminated the 5 arrows furthest from the median in each group. Then took the medians for the two 10 arrow sets and found the difference.

For a 10 gr difference the result was 3.375 inches at 70 meters.
Arrows were 348gr at 284 fps for the 65gr tip and 358gr at 281 for the 75 gr tip.

I have to admit, this much difference shocked me. Basically a 1/3 of an inch for every 1 gr.


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## limbwalker (Sep 26, 2003)

> I like the weight of X10's, while some archers will need a lighter all carbon shaft.


My Nano Pro's weigh right in-between my old ACE's and X10's. IMO, this gives them the perfect weight for an outdoor arrow. Not too heavy to get good sight marks, but not so light that they get tossed about downrange.

And I'd love for anyone to prove that X10's have less drift than a Nano Pro. Mathematically, it just doesn't work out...

John


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## caspian (Jan 13, 2009)

I believe James Park, who now has a PhD in mechanical engineering based around the dynamics of arrows, has done the analysis. moreever, he's still shooting Protours.


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## calbowdude (Feb 13, 2005)

I too would like to see that data expounding the X10 has better wind drift than Nano Pro. 

I am definitely not disputing that aluminium tubes can be made extremely straight. I simply am stating that I suspect there are more steps involved in making a alu/carbon arrow, and more chances for tolerance stacking.


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## Joe T (Apr 5, 2003)

limbwalker said:


> My Nano Pro's weigh right in-between my old ACE's and X10's. IMO, this gives them the perfect weight for an outdoor arrow. Not too heavy to get good sight marks, but not so light that they get tossed about downrange.
> 
> And I'd love for anyone to prove that X10's have less drift than a Nano Pro. Mathematically, it just doesn't work out...
> 
> John


No one, as far as I know, has ever determined the relationship if any between wind drift and arrow performance. Just measuring wind drift by itself is quite meaningless. The only way to determine the "best" arrow, as already mentioned, is to shoot lots of different arrows and see which overall gives you the highest average score. (there are different approaches to doing this e.g.minimizing groups). You can of course then extend this approach to a group of arrows as in competions you you don't just shoot one arrow. This score of course relates to the overall arrow (physically) or set of arrows (includes physical variations), not one specific arrow property.

Different archers will have different draw lengths, draw weights etc. and so be using physically different arrows. You cannot therefore generalise the "best" arrow across archers except in the crudest way. You can probably generalise that carbon arrows will perform better than wooden arrows but you can't say that brand x carbon shaft is better than brand y carbon shaft.

So whether your talking about acceptable weight variation or wind drift properties the only valid approach is for the individual archer to sensibly test the likely looking candidates to determine what works best for that individual archer.


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## Greysides (Jun 10, 2009)

http://www.carbontecharrows.com/main/arrow-spine-weight-and-straightness/


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