Pattern Question

Not enough difference, if any, to be concerned about. With modern smokeless powder and shock absorbing plastic cup wads most guns are over choked. The choke is at the muzzle end of the barrel no matter what the barrel length and it is that end that determines how tight you pattern will be. There is a good article in Shooting Sportsman by Michael Macintosh who says we would all be better off to shoot cylinder bore for wing shooting since the plastic cup wad creates a pattern at least on choke size tighter than what the choke is designated.

The modern powders will do their job in 18-20 inches of barrel length. The 26" could actually out perform the 28". Depending on the game you are trying to aquire, and the shot type you are using, full is usually not needed today. All around a modified or improved cylander is usually a better choice. Barrel length is more a comfort item than a functional question with today's ammo.

Thanks John
I guess that age old rule of thumb use to be a longer barrel
supported a tighter pattern was stuck in my head.

Back when ammo used over the powder felt or paper wads that did not protect the shot from rubbing along the barrel it may have made a difference in pattern, that is why copper and nickle plated shot was made, to prevent deformation and fliers. Today, barrel length has more to do with a smooth swing and balance.

It's all about finding the best choke/load combo these days as far as achieving tight patterns.