See Davies 'The Better Shot' for a pretty good description of what we're talking about here as far as gun mount technique.

Assume a 'ready' position, follow the bird with the muzzle while pushing out and then pulling in.

The stock butt rubs on nothing on the way to 'the pocket'.

Friction in the stock butt/shoulder pocket interface helps your cause... thus checkered and grooved buttplates.

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