As I was reading about 22lr rifles I found some articles on Anschutz torque setting and there effect on accuracy.
One article stated that by torquing the action to the stock from 4.5 to 4.6 Nm showed a significant improvement in accuracy. Going above 4.7 accuracy dropped off.
That made me wonder if there are specified setting for the Hammerli SP20.
I contacted several sources over a period of 2 month. Most of them would not reply.
Fortunately 2 reliable sources did reply. One of them was the Walther/Hammerli factory.
the values they gave me were as follows.
Answer 1 (out of privacy considaration I will not mention his name)
The two screws clamping the barrel have no specific torque, do just normal tighten.(2-3 Nm)
Tightening the three front screws is just bit more tricky, because of the
distribution of forces.
When mounting, first tighten the bottom
screw with a torque of approx. 3 Nm.Then the two upper screws with approx 2 Nm
Answer 2 (Walther/ Hammerli)
Not more than 1,9 Nm (just "hand-proper").
As both values are quite close I feel that using any of the two answers/settings would be safe.
I use a Wiha I-torque torque screwdriver 1,0 to 6 Nm 36888
When using this torque wrench I do the initial setting on the wrench and then "test" it 2 or 3 times on an allen head screw that I fastened to a piece of pipe. Just to make sure that the initial setting repeats itself and the the setting "feels"right.
Remember: 2-3 Nm feels like just around hand tight.
It takes a 3 mm allen head bit to fasten the 3 barrel holder bolts.
To prevent damage to the barrel holder coating I turned down the neck of the bit slightly.
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| Right is bit with turnded down neck |
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| Bit fits barrel housing without interference |
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| Wiha I-torque torque screwdriver 1,0 to 6 Nm part no. 36888 |
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| Improvised "Test"tool" |
As additional information I include 2 exerpts from this forum discussion:
http://www.targettalk.org/viewtopic.php?t=9787
Member XXXXX
the torque setting for the three front screws of the SP20 is vital for consistency and overall frame rigidity; I do not recall this setting value as I only have the adjustment position marked on my own ratchet driver I keep with the pistol (sorry).
Reaction Member YYYYY
" Hmm. I find the comments from XXXXX vaguely disturbing. The manual with the gun makes no mention of any specific torque setting for the three screws that hold the barrel to the frame, whether .22 or .32, only cautioning to "Absolutely use all 3 screws!". No kidding. Given that I swap barrels for the centrefire portion of each practice/match, having to use a torque wrench to do so would be a major pain in the a$$........"
