Even with a scope, shooting at 100 yards requires considerable practice. I shot many thousands of round with my Redhawk .44 mag. Very enjoyable pastime but the scores at 100 yards would not have been possible without much time at the range.
I believe a red dot would be more suitable for what you want. For a scope, do not go over 2X.
Be prepared to also buy a new set of high rings as many scopes won't work with the factory supplied rings.