Since these are factory rounds, I am not sure of the cure, except to use different ammo.
Let me tell you about my experience with keyholing and reloaded revolver ammo. When my revolver reloads keyhole, there are one of two solutions that usually work, more powder or more crimp. In both cases, what happens is slightly faster bullets.
I think that the ammo you were using, for the barrel (which is where diameter and if it is leaded comes in) was going to slow to properly spin stabilize.
A 2 to 2/5 inch barrel will probably have the slowest velocity of a given factory load of ammo in a particular caliber. The same ammo out of a 4 inch barrel might be just fine.
My suggestion is if you like the snub nose revolver and it shoots jacketed ammo fine, buy the gun and just keep trying different ammo until you get what you think is the perfect combination.