A couple of things come to mind.
First off, if you load a shorted case in a longer cylinder, (38 spl in a .357 chamber) you can get fouling to where a build up happens & you have problems chambering a .357 case later on. Often, folks have to spend some serious time cleaning a cylinder's chambers extensively to get them to chamber the longer cases.
Second. The chambers are cut for the longer cases,,, and as noted above by Bob,, you MAY get a slight "wobble" of the bullet as it moves down the chamber & into the barrel's forcing cone. If it enters a little "off" it can easily affect accuracy.
I have played with my .454 Casull Freedom Arms in using a reduced load. I use nothing but .454 cases to avoid the chamber fouling,, AND to assure the bullet is supported by the case as much as possible until it enters the forcing cone. I can get 3"-4" groups at 100 yds with this.
Then there is the fun I've had learning about the process of "deep seating" a bullet. In my .357 Maximum, when loading the heavy & longer bullet designed by David Bradshaw & Lee Martin,, we deep seat the bullet to where the crimp is over the front driving band. And accuracy is excellent. BUT,, that bullet is also longer for caliber, and was designed to be loaded that way.
All this is shared to allow you to realize there's not always a cut "n dried answer to your question. The best thing to do is to "experiment & see what YOUR gun likes & dislikes, in YOUR hands on YOUR range.