Most of differences expressed here are semantic. You don't get common points of impact with a side by side shot with typical gun mount -- out to infinity or otherwise -- without barrel convergence.
"Theoretically" ... if the load is perfect for the gun's barrel convergence, the barrels are perfectly parallel to the "line of aim" when the shot leaves the muzzle, and the pattern centers are delivered to virtually the same point at all distances, without crossing. Patterns shot with a lighter load cross at some distance; with a heavier load, the pattern centers never coincide, and divergence increases with distance.
As noted before, lots of factors can muddy actual results. The above assumes consistent velocity. It also seems to me that even cast could affect how much each barrel of a side by side moves before the shot exits the muzzles.
Jay
Last edited by Gunflint Charlie; 05/09/13 12:58 PM.
