Because single action grip frames vary in size custom grips are often a little oversized to allow fitting to an individual gun.
However, those seem inordinately large and I wonder if they were intended for a larger type revolver.
If the grips are checkered and fitting them to your gun would cut into the checkering, I'd suggest they were for a different gun.
I'm not sure what to do in this case.
If fiting them would damge them, I'd consider returning them or selling them and buying something that would be a closer fit.
There are plenty of SAA replica grips available.
However, those seem inordinately large and I wonder if they were intended for a larger type revolver.
If the grips are checkered and fitting them to your gun would cut into the checkering, I'd suggest they were for a different gun.
I'm not sure what to do in this case.
If fiting them would damge them, I'd consider returning them or selling them and buying something that would be a closer fit.
There are plenty of SAA replica grips available.