Sounds like not much help from Weatherby. You would think if you have a carbon ring you would being seeing pressure signs on every round. Couple of things you could look at. Measure case necks of a loaded and a fired round, or you can try sliding a bullet in a fired case. May be some of the brass necks are a little thick. Measure the belt above the ejector groove before and after firing. Usually the expansion will be consistent and gives an indication if the loading is consistent or not. Could try using a .270 or .30 caliber brush in the chamber neck to make sure it is clean or try to find some bore paste to see if that helps.