" I call the bracket at the mid-point the centre hanger and it does have an effect on point of impact. If you look cloely you will see that there are fine grooves along the edge of the block attached to the barrel. If you slacken the screw and then gently squeeze the barrels together at mid-point, holding them in that position whilst you re-tighten the screw, you will lower the point of impact of the bottom barrel. Conversley, spreading the barrel gently will raise the impact of the bottom barrel. If you think about this you will understand that squeezing the barrels together puts an upward curve in the bottom barrel, this depresses slightly the muzzle end. the top barrel does not bend as it has the rib acting as a strengthening brace on its top side. Spreading the barrels puts an upward curve in the bottom barrel thus raising the muzzle a little.
As to the question of slackening the screw whilst changing the front hanger it will make a difference although there is no real need to do this. Logically, leaving the screw tight will cause the bottom barrel to bend over a shorter distance - centre to muzzle - consequently a change of hanger size will theoretically have a greater effect than if the bend was spread over the whole barrel length. Personally I like to slacken the screw before changing the hanger as I prefer the bend in the barrel to be a more gradual curve from breech to muzzle. Something in my mind regarding stress etc. There is however no need to do this, or so I am advised. Just call me quirky." Alan Rhone http://www.krieghoff.co.uk/1.html
Here is my issue with the bottom barrel POI. It has a number 4 hangar and this generally yields a parallel POI to the top, or so it has on my other K-guns with a flat rib. My bottom barrel shoots 6-7 inches higher than the Top barrel at 20 yards. Would you A, put on a number 5 or 6 hangar, or B, adjust the center hangar for the difference?
Does anyone have the data that tells what each hangar size gives you for change over a set distance?