Is there a known problem that typically causes horizontal stringing?

My 30-06 loads, 180 gr. Accubond over 56.0 gr. N160, CCI 200 primers all charges weighed, selected RWS brass +/- 1 gr. bullets .15" off the lands.
10 shots spread upto 2,5 inches horizontally, but no more than 0,8 inch vertically at 100 meters.

Not any expert of course, but nearly all my new Remington M700's had East-West stringing after barrel warmed up, related to barrel touching stock. This problem went away completely after having barrel free floated, action glassed and trigger job, so get out your dollar bill and see if barrel is touching....r in s.

Wind, wind and, often times, wind.

Verical is usually not enough powder in the case. Horizontal is usually wind or inconsistently addressing the trigger or trigger pull.

Let me emphasize what eddieharren said!!!!
Wind, Wind...etc

muck

inconsistant bedding --free floating may or may not cure it--, wind, bench technique.
Your barrel may not be centered in the stock and the pressure point may not be bearing correctly in a upward manner. If you have a pressure point, take the end of the barrel in one hand and the stock in the fingers of the other and see if the stock and barrel can be wriggled back and forth independently. If so, try putting a biz card between the pressure point and the barrel and trying that.
The other two are self explanatory. A simple stick with some surveyors tape tacked to it halfway to the target and again at the target will help you with the wind. You don't have to wait for it to be dead still, just try to shoot when things are the same.
The last item just takes concentration and practice, practice, practice. A session of dry firing before you go live helps. Are the sights in the same place AFTER THE TRIGGER FALLS as before? If not, why not. They should be if you are using proper bench technique.

Almost everything I've read says it is the result of wind or flinching.