Snake shot generally (but not always) shoots tighter out of short barrels for several reasons.
1: The reduced barrel length imparts less spin to the shot column/capsule as it heads downrange, reducing the amount of opening up the shot pattern does.
2: The lower velocity (slightly) means that less shot is disturbed and blown out of the pattern by muzzle blast or centrifugal force.
3: The capsule is normally destroyed by the rifling but not always, in some wheelguns with very shallow rifling such as the 1917 Smith's, you don't always get capsule destruction until the velocity gets high enough (for you handloaders).
The auto's like the Glocks and H&K's with the Polygonal/Hexagonal rifling work surprisingly well with shotshells. The "smooth" rifling seems to disturb the pattern less than any other type of rifling available today to the handgunner. If they function the action, you're set, if not all you have to do is remember to cycle the action. And believe me you will remember.
The fly-weight wheelguns tend to have issues with different types of ammo, including shotshells thanks to inertia. Steel framed guns are the least problematic, aluminum ones next, the Scandium and Titanium ones seem to have the most issues.
I shoot a decent number of snakes every year with the CCI factory products and have done so for years, enough so that I load for the .38/.357/.44Spl/.44Mag/.45AR/.45LC just so I can afford it. I have to purchase the 9mm, .40 and .45 Auto products as I'm just too cheap to purchase the RCBS dies for .45ACP.