I'm sure that case taper might affect bolt thrust, as I know that the finish in a chamber can affect it, but it would be foolish to use it as design factor for a build, because so much could affect it, a dirty chamber versus a clean one, for one. And if you had a case head seperation, the brass sticking to the chamber wouldn't help at all as the case head would generate all the bolt thrust, and if you're on the line at all, it might just be enough to do bad things. This is just my opinion take it for what you will, but when I decided to build a big 338 on a savage action I decided on an Edge, and not a Lapua. Here are some articles by Dan Lilja on the subject ( Lilja Precision Rifle Barrels - Articles: A Look at Bolt Lug Strength
) (Lilja Precision Rifle Barrels - Articles: 378 Weatherby Cases in the Remington 700 Action?
) the last one is on using a .378 weatherby case or a rigby on a 700 but It's still good reading. If you were to go the lapua case in the savage action, I wouldn't use a barrel nut and fit the barrel with a shoulder. People use the rem 700 with the lapua cases and the savage should be just as strong, and it's got finer threads on the barrel shank (same dia) so the threads cut less deep into the chamber end on the barrel. Just some info to chew on. Personally I'd use the Edge.