Interesting. I had a Encore PH 28" 280Rem that shot 0.5 MOA with 140BT's. Sold it and
wish I didn't. Lot of Encore accuracy problems are associated with 6#+ trigger plus slow hammer drop. Changed springs out to 2.5 trigger and 58# hammer spring which improved locktime. Thumb gets serious work out pulling back hammer!!! I would bet the hammer spring may have as much impact on the accuracy just speeding up locktime. When I did that the accuracy with PH 28" barrels improved across the board.
Every barrel will fail that whip test even on a bolt gun unless probably full bull. He is 100% correct on harmonics but that is what we do as loaders to find the load that matches barrel harmonics instead of cutting the barrel to match factory ammo harmonics.
Encores are unique and there are other factors on accuracy different from bolt guns. Forearm isolation from barrel and consistent placement of forearm on rest is absolutely critical for consistent accuracy.
We should know that barrel length gains maybe 25-30 fps per inch depending upon cartridge, powder burn rate and of course bullet. But if I want to add 100 fps this is one way to do so. Virtually meaningless velocity gain to most but to me is ALL I really care about. Why are there 30" barrel bolt guns? Because that person wanted one.!
Barrel length with straight wall is entirely different animal and comparing apples to bowling balls.
And yes I know Mike and have had a lot of discussions with him on variety of Encore topics.