Weatherby rifles (and Remingtons for that matter) are very sensitive to the torque of the action screws, particularly the front one. I'd loosen it all the way out, then tighten it up to 50 lbs. Then try tightening in 1 lb increments between groups until to see if it improves.
1. That's "inch pounds", of course, not foot pounds.
2. The barrels on the Ultralights don't seem any "whippier" than other Weatherby barrels, unless the fluting affects the rigidity. It's the same #2 contour Weatherby has used for years.
3. My own Ultralights in .270 Wby are pretty consistent 1" to 1-1/4" shooters with 140 or 150 grain bullets, not so hot with 130's. One has a floated barrel, the other one doesn't.
