It is reasonable to say that certain single shot weapons have such heavy recoil that they must be realigned with each shot. The Ruger Superwarhawk is one of them. Being an Alaskan hiker and hunter, I'm somewhat familiar with the S&W-629 44 Magnum revolver. While it is totally possible to shoot all six rounds in a 44 magnum revolver in one initiative pass (1 second if you're fast as greased lightning, 3 is you're slow as molasses), only the first would be in the ballpark of the target. Similarly, each of the SS weapons have some intrinsic quality that needs to be reset after firing. Pump action shotguns and bolt action rifles, for instance.
Now, there are exceptional individuals who can shoot such a weapon accurately faster than a semi or fully automatic equivalent can fire. Those individuals are the exception, not the rule, and tend to have skill ratings out of grasp of the average shadowrunner (in the 8-12 plus specialization range). I would say that the GM should have free reign to houserule such circumstances if they choose, but it's not really in line with the very average people that shadowrunners tend to be and tend to run into.
Custom qualities as the situation warrants, perhaps?