What Powell might be trying to express instead of 'feels more alive in your hands' could be 'feels more alive when mounted'.

There's a difference. If the weight is moved aft so the gun is muzzle light and butt heavy it will indeed be more 'lively', as in easier to move to the target.

This would be Don's 'mounted swing effort' as I understand it.

"The price of good shotgunnery is constant practice" - Fred Kimble