Originally Posted by Muletrip
Also would there be any barrel harmonic problems with a #3 contour barrel at 26".
No barrel has harmonic problems. Each one has ony one fundamental frequency (typically 100 Hz or less, the one that causes the most angluar change in bore axis at the muzzle while the bullet goes down the hole in it) and harmonic (multiples of the fundamental at higher frequencies; meaningless for accuracy) for every round fired through it. Bullets are long gone before the barrel goes through one major vibration cycle at its fundamental frequency. As long as bullets leave at about the same place in each cycle, good accuracy is attained. Most bullets leave on the muzzle's up swing which is good because those at lower velocity depart at a slightly greater angle which compensates for its slightly greater drop; faster bullets leave sooner at a lesser angle but they don't drop as much.
The fundamental frequency of a given barrel changes when a receiver's screwed on its back end; the size and shape of that chunk of metal parts just changed. It changes again when a scope's mounted on the receiver. Bolting that scoped barreled action into a stock changes it a bit more.