Measured best sight extension length

[James Park]

I tested my AR34 in the Hooter Shooter to find the best sight extension length.
With X10's, size 500, the optimum length was with the sight pin 230mm in front of the grip.
(The brace height is 200mm, so it does not equal that).

[puddin]

thats intersting i never really took much notice of sight extension. i always just put it to get goo sight picture.
what wort of criteria did you judge it on. was it a combination of sight picture and acuracy or something totaly different??

[Leighton]

Jim, do you think there is a formula?

[James Park]

I am thinking about the maths, but a way to go yet.
If you get the extension correct it cancels out the effect of any bow torque.

[primal]

I tested my AR34 in the Hooter Shooter to find the best sight extension length.
With X10's, size 500, the optimum length was with the sight pin 230mm in front of the grip.
(The brace height is 200mm, so it does not equal that).

hay jim is that equal to the point where the strings run over the cable gaurd?

[James Park]

hay jim is that equal to the point where the strings run over the cable gaurd?
No.

[Stace]

Sorry to ask a daft question James but did you just try it in all positions before deciding on the optimum set up?

I'm expecting delivery of my new bow next week and want to set it up correctly from the beginning.

[James Park]

Stace,
What I do is:
- Shoot the bow properly, ensuring you are not twisting the riser.
- Adjust the sight so that you are hitting the centre.
- Now deliberately twist the riser a little (not too much otherwise the string might fall off).
- If you twist it anticlockwise (as seen from above), it is convenient for a right handed archer as that avoids the string hitting your arm or the arrow hitting the cables.
- Then, if the arrow now hits to the left you need to have the sight extension longer. If to the right it needs to be shorter.

Using the Hooter Shooter: I have set the HS up to do exactly this, with a set force applied to the riser so I can very repeatably do the test. (However, it does work excellently without the HS).

Of course with all this it is much better to not twist the riser anyway. What this is doing is ensuring that should you happen to twist the riser unintentionally, it will have minimal effect on where the arrow hits.
(That is: it is making the bow "more forgiving" - perish the thought).

[Stace]

By twisting the riser I assume you are taking a tighter grip to avoid the bow returning to it's optimum position?

Or do you reposition the wrist position?

[James Park]

Twisting the riser:
This can happen due to poor hand position, for example, in normal shooting. My experience is that a large proportion of archers do end up twisting the riser, even though they do not mean to do so. It is one of the reasons archers can have trouble tuning bows.
In the test above: I deliberately take a firmer grip on the riser and gently twist it a bit. Do remember that if you twist it too far the string could fall off (nasty) - hence, be careful.

[Stace]

Top stuff James, thanks for the info and your patience.

[The One]

Would just like to ask if this works for a recurve, and if not, why not? Think we've been through this before, but I forget the reasons.

[James Park]

Yes, it does work for recurves - the mechanics is the same. However, I have not measured the relevant sight extension (your opportunity for fame is right here).
Note that it is much more difficult to twist a recurve than a compound, and hence the bow torque problem is less.
The difficulty of twisting a bow is related to the brace height and the holding weight. Higher brace heights and holding weights (as is the case with a recurve compared to a compound) increase the resistance to bow torque. This is a key reason why compounds with lower brace heights are more challenging for the average archer.

[The One]

Cool. I'll have a go sometime and see

[Flex]

230mm from front of the bow too the sight. Just wondered what is the distance to the tip of the arrow rest from the string? Thinking it must be close to 230mm...

just a thought.

[Marcus]

brace height is to the thoat of the grip, and most archers run their rest so it is above that point. So that's not it either.

[reversehaven]

cool.. i didn't even know this affects shooting! ill go give it a try tonight.