Chris,
I just took a Rob Haught Combat Shotgun class. I did a review of it here:
http://www.thehighroad.org/showthread.php?threadid=82294&highlight=Rob+Haught
This is what he taught:
For a combat load of a dry gun, he teaches two methods.
The first, you mantain your strong hand grip, run the slide to the rear, rotate the gun counterclockwise to that the ejection port is facing up, grab a round with your weakhand, put it in the chamber, close the slide, and fire. The gun stays pretty high up using this method. This is pretty fast. This works when the spare ammo is carried weakside(right hand shooter).
The next method, you run the slide to the rear, bring the gun down to about mid torso, grab the gun with your weakhand so that your fingers are just under the ejection port, to the rear of the slide and in front of the 4rd sidesaddle(he prefers the 4 round for this very reason, there is no room to do this with a 6rd sidesadde), let go of the gun with your strong hand, access your spare ammo with your strong hand, put the round in the chamber, reaquire the gun with your strong hand, run the slide forward, and fire. For most of us, this method was faster than the first, because we were using our strong hand, I believe, and were more dexterious with it. This works when the spare ammo is carried strongside(right hand shooter).
He likes to keep 2 rounds up, 2 down, in the sidesaddle to accomodate either loading method. Also, he says to have spare rounds on both sides of your body to accomodate either method.
There may be other instructors teaching these methods.
Dave