I very much appreciate the advice. It left me thinking that much of what I have read about this subject must be wrong:
Brister, Shotgunning: The Art and the Science p. 84
“Many shooters have a problem with the stock catching on clothing beneath the armpit in fast-mounting situations. This can be helped by grinding off the top of the recoil pad (the heel) so that there are no sharp corners or angles to the pad. Additional insurance against this problem (which has cost many a quail, woodcock, and grouse) is to paint the sides of the recoil pad and also the rounded off area at the top with clear fingernail polish. Do not paint the portion of the pad that will rest against your shoulder; you don’t want that part slick because you want the gun to stay securely in position at the shoulder during recoil.
Churchill, Game Shooting p. 29-30
“In practice, the butt should scrape your clothing as it travels up your arm to bed in your shoulder. The slightest clearance between butt plate and shoulder is all that is necessary or desirable; and the thrust of the left arm automatically provides it.
At the completion of the mounting movement or, rather, this first portion of it, the gun is up to eye-level and the butt of the stock in touch with but not home on the shoulder. . . . Now, put your shoulder forward to the stock and at the same time contract the trigger finger so that as the gun is firm against the shoulder the trigger is pulled exactly at the limit of the movement.”
Bowlen, Wingshooting Handbook p. 34-5
“The key is to bring the shoulder forward to meet the buttstock rather than pull the gun back to the shoulder. The heel of the stock should slide up the face of the shoulder as the gun is mounted. As the gun comes into the cheek, the shoulder is rolled slightly forward in a sort of shrugging motion. This motion snugs the shoulder and stock together and minimizes recoil. . . .
You should not pull the gun back to meet the shoulder because doing this has a tendency to interrupt the natural flow of the shot. . . . If the gun is pulled back to the shoulder, this natural weight shift [forward towards the target] is interrupted. As the gun is pulled back, there is an inclination to shift the weight back. Typically, the weight will be shifted to the back foot. As your weight falls back, the muzzles will rise and in many instances cause you to miss over the bird. Rolling your shoulder into the gun accentuates the natural weight shift. . . . Pulling the gun back to the shoulder tends to shift your weight back onto your heel and interrupt your swing.”
Yardley,
http://www.positiveshooting.com/MountandSwing.html“Advice on the starting position for muzzles and butt varies. Let us try to keep it simple. I would consider it a mistake to hold the muzzles above the line of any crossing clay bird. The British instructor Percy Stanbury, advised keeping the muzzles well up - touching the line of sight - and butt fairly low. Robert Churchill, advocated an unusual starting position with the butt tucked in under the armpit and the muzzles low - parallel to the line of sight. This has also been adopted by the Holland and Holland Shooting School. In the case of the first mentioned style, the gun should pivot about the axis of the muzzles as the mount progresses. It should also be pushed towards the target with the shoulder going forward to meet it as the mount is completed. In the case of the Churchill mount there is an exaggerated pushing out of the gun as the mount commences and a less obvious movement of the shoulder to the gun at the end (although Churchill would have argued the point).”