You didn't say how high you want the gun to ride or if you'll use the holster for concealment also. I have an old Roy Baker pancake holster for my S&W revolver, but I think Roy's leather is no longer in business. You may want to look into something by another maker. Surely someone makes a 3 slot pancake that will fit the King Cobra.
As far as the holster being "tight", in my humble opinion I want the holster to fit tight enough that the gun won't "fall out" with the safety strap undone. And leather will stretch more than it will shrink. If I buy a holster that is not formed for a particular gun I soak the holster in water until it is saturated then put the gun in it and form it with my fingers and leave the gun in it overnight until it dries out. Just be sure to clean your gun afterward.