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Shaft length

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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pecky762

New Member
Dec 7, 2019
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0
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Hello all

Was wonder what is the shortest length spear people have run on a Rob Allen 120
Closed muzzle. Wanting to run a shorter spear for less overhang.

Cheers
 

hteas

Well-Known Member
Mar 9, 2005
961
137
148
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You probably need to go with a 150 if you are using a 6.5 dia shaft. If you go with a thicker shaft you can get away with a shorter length. I use a 140x7.0 on myRA 110, but a 140x6.5 shaft developed enough shaft whip to make a lot of noise and accuracy suffered substantially.The basic problem is that the shaft can develop a harmonic that causes the whip.
 

pecky762

New Member
Dec 7, 2019
3
0
1
43
You probably need to go with a 150 if you are using a 6.5 dia shaft. If you go with a thicker shaft you can get away with a shorter length. I use a 140x7.0 on myRA 110, but a 140x6.5 shaft developed enough shaft whip to make a lot of noise and accuracy suffered substantially.The basic problem is that the shaft can develop a harmonic that causes the whip.
Was thinking 7.5mm shaft. And twin 16 or 14 rubbers. 120 takes a 160 shaft was looking at 150
 

hteas

Well-Known Member
Mar 9, 2005
961
137
148
72
My guess is that it would work. Just don't overload it. I use 2x14mm bands with a 3x stretch.
 

NicholasCLF

Member
Oct 27, 2016
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I’ve used a 150x7mm Shaft with 2 x 14mm bands on a 120 RA gun already. Had no issues. Can’t go any lower as the flopper would end up on the muzzle/gun.


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