How to determine length of buttstock?

Southpaw · Post by **Southpaw** » Sat Sep 11, 2004 12:12 am

What method is most accurate in determining the length of the buttstock for a particular individual? I've heard/used the length of the inside of the forearm - from the trigger finger to the inside of a bent elbow. What other methods are used.

Regards,

Southpaw

GaryN · Post by **GaryN** » Sat Sep 11, 2004 11:47 am

The method you mentioned is just the "starting point" as it only measures forearm length.
From there my AR coach looked at me holding the rifle in the stance, to see how the rifle fit in position, then he made further adjustments.

gud luk
Gary

Martin H · Post by **Martin H** » Mon Sep 13, 2004 11:14 pm

For prone, this is the guide line that I use:

With arm held down at your side, measure from inside of armpit to tip of fingers. Halve the measurement and this is the butt length to start with. A straight position will be a little shorter and a more angled position will be a bit longer.

Cheers
Martin

Southpaw · Post by **Southpaw** » Tue Sep 14, 2004 1:05 am

Thanks Martin. A different approach is what I was looking for. I'll try the method you outlined.

What are the indicators that would necessitate an adjustment in length, beside just general comfort? Are there physical signs to look for?

Trial and error is not as easy when using spacers as opposed to a free rifle type buttstock.

Any further help appreciated,
Southpaw

Albert · Post by **Albert** » Tue Sep 14, 2004 6:20 am

For my certificate as a Basic-trainer I made a small study about the arm leng versus the butt length. Here is a list with the measurements taken from several shooters ranging from middle class tot top class shooters in the Netherlands.

Dimensions in millimetres

I = Distance buttplate-grip[L1] : Distance grip-handrest[L2]
II = armpit-elbowpit [A1]: armpit-end of middle vinger [A2]
III = Ratio I versus Ratio II
IIII = Posture of shooter
Kneeling
I II III IIII
1 315 : 315 205 : 665 1: 1,0 - 1: 3,2 Normal
2 294 : 332 210 : 650 1: 1,1 - 1: 3,1 Normal
3 323 : 424 260 : 760 1: 1,3 - 1: 2,9 Long
4 300 : 306 230 : 703 1: 1,0 - 1: 3,1 Normal, firm build
Prone
I II III IIII
1 337 : 357 240 : 740 1: 1,1 - 1: 3,1 Normal
2 297 : 303 275 : 710 1: 1,0 - 1: 2,6 Big, firm build
3 312 : 347 250 : 730 1: 1,1 - 1: 2,9 Big, firm build
4 305 : 320 210 : 650 1: 1,0 - 1: 3,1 Normal

[L2 = aprox. 1,05xL1]

Comparing [L1] with [A2] we find the following ratio:
Kneeling
[L1] [A2] Ratio
1 315 460 1: 0,68
2 294 440 1: 0,67
3 323 500 1: 0,65
4 300 473 1: 0,63
Prone
[L1] [A2] Ratio
1 337 500 1: 0,67
2 297 435 1: 0,68
3 312 480 1: 0,65
4 305 440 1: 0,69

The distance [elbowpit to the starting point of the middlevinger] is aproximatly the same as the measured distance [L1].
Therefor this is – as mentioned in the forum – a good starting point.
It will be interesting to find out if the distance [L2] equals the distance as mentioned by Martin H. He is correct in saying that the distance will become longer with an angled position and shorter in a straight position.
In general: when butt length is to short, the rifle starts moving sideways on the ritm of the heartbeat, when butt length is to long an erratic uncontrolled sideways movement occurs.

Good luck
Albert Thijsse (The Netherlands)

Guest · Post by **Guest** » Tue Sep 14, 2004 7:26 am

When the butt is set at the right length you hand should fall naturally onto the grip.

You could try starting with the butt at its shortest setting, getting into position (you didn't say which) and closing your eyes. With your eyes closed drop your hand onto the stock. This will hopefully let you do so naturally. Open your eyes; if your hand is ahead of the grip you will need to move out the butt by the appropriate length. Most rifles are designed to be short enough for most adults. If you are 5' or under you may nedd to get out the saw!

Tim S

Exeter UK

Southpaw · Post by **Southpaw** » Tue Sep 14, 2004 8:38 pm

Hey, this is some great stuff. Thanks Tim and Albert.
I shoot 3-P so I'm also was also wondering what changes needed to be made from position to position.

I'll have to get my tape measure out and get to work.

Southpaw

Albert · Post by **Albert** » Wed Sep 15, 2004 1:58 am

For a starting point and starting with the length 'armpit-top of fingers', using the measurements of the matrix I gave, the buttlength is APROXIMATELY:
kneeling: 0,45 'armpit-top of fingers'
prone: 0.47 'armpit-top of fingers'
standing: 0.46 'armpit-top of fingers'

Albert (the Netherlands)

Martin H · Post by **Martin H** » Wed Sep 15, 2004 7:23 pm

Albert,
In prone, for the length of trigger to handstop , we have used the the formula of half total arm length (as mentioned above) minus 50mm. This seems to be a good starting point for the front length.
Cheers
Martin

Guest · Post by **Guest** » Thu Sep 16, 2004 1:20 pm

Anonymous wrote:When the butt is set at the right length you hand should fall naturally onto the grip.

You could try starting with the butt at its shortest setting, getting into position (you didn't say which) and closing your eyes. With your eyes closed drop your hand onto the stock. This will hopefully let you do so naturally. Open your eyes; if your hand is ahead of the grip you will need to move out the butt by the appropriate length. Most rifles are designed to be short enough for most adults. If you are 5' or under you may nedd to get out the saw!

Tim S

Exeter UK

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