Tuning - Walk-back Tuning (Berger Method)
The bare shaft or planing test allows archers to set-up the basic tune of there system bit has one draw back in that it is difficult to separate out the combined effects of pressure button centre shot and pressure. The walk-back tuning method allows these effects to be individually assessed by analysing the falling patterns the arrows make.
The test must be done when basic matching has been achieved and after the nocking pont and bracing height have been optimised. The test comprises of a series of arrows shot at the same aiming point (without adjusting the sight) at increasing distances away from a target (typically 5, 10, 15, 20, 25, 30, 35 and 40 yards). The test may need two butts, one on the target stand and one on the floor leant against the other to allow sufficient "fall". Like bare shaft tuning, it is not advised for novices to undertake this test as it requires some degree of consistency in shooting and release.
If you are uncomfortable with your consistency then you can shoot several arrows at each distance and draw around the groups taking he group positions rather than single arrow positions. Ideally you should correct for button position first (correcting the curved line) followed be button pressure (correcting the angle of the straight line)
Further reading and references
This subject is very well written up in Murray Elliot's Archers Reference. I would recommend you take the time to read his section on tuning (including the Rick Stonebreaker stiff-plunger method).
Stages of Tuning
- Basic bow set-up and alignment
- Basic nocking point and bracing height set-up
- Centre shot set-up
- Bare shaft tuning
- Walkback or Berger method tuning