Terrible! I have not used them in a Walker, but in other revolvers. The rifling spins the shot, and you get a NON-pattern with the stuff. Out to 25 feet, maybe you get a majority of very small shot to hit a 2 ft. sq. target- maybe. Better to use it inside 12 feet.
Because the cylinder is so small, and you can't duplicate those shot cartridges with the plastic pills filled with shot that are made for the .44 cartridge guns, You have to use very small size shot, and usually less than 1/2 oz. You just don't get much of a pattern, and the individual pellets just don't carry much energy when you have to use #6 or smaller shot sizes.
At most its a snake gun load- hardly worth the bother, since you can move a snake out of your path with any stick, or simply choose another route. The loads may kill small rodents, and even small game, but that is about it. For anti personnel, the shot needs to be fired inside 10 feet, and then aimed at the face. But at that distance, just firing the gun is going to send out a long flame that can reach the assailant, or at least blind him with its flash, and then obscure you in the smoke so that you can evade your assailant before he can find you. The noise will deafen his ears, and cause him acute pain in both his ears. If he is hit by any of the shot, the stinging sensation will be like nothing he has every felt before. If he is high on drugs, or drunk, of course, he may not feel much of anything and just keep on coming at you. I would much prefer to recommend you use RB loads for social situation, if this were the only gun you have to protect yourself and other innocents.
I cannot balance the limited performance of such shot loads in a ML revolver, with the extremely heavy weight of these Walker guns. The gun is just too heavy for this kind of load, and is far more capable of sending a single RB or conical accurately out to 100 yds. and beyond, instead. Why would anyone want to load shot into a Walker Colt? It only sounds like a " neat " idea until you actually look at the problems you face getting such a load to hit anything. This is a revolver with the size, strength, and caliber to use to take Whitetail deer out to 100 yards. Why would you limit by loading it with shot that make it a 10 yd gun or less????
If you have never loaded shot loads in revolver, or pistols before, you need to use OP wads between the powder and the shot, and then either a .44 caliber gas check( for the bases of modern cast bullets) or another strong wad to hold the pellets in the chambers while surrounding chambers are fired. The wads will be pushed aside by the load as it leaves the muzzle, but they will affect how the shot patterns, since the wads will be spun by the grooves of the rifled barrel. The biggest danger of shot loads in a revolver is the thought that they might permanently blind an assailant. There are only a very few areas on the human body where a shot charge can hit and prove lethal. Unless at very close range, death will take its time coming.