pro2a
A 100ft is only 33 yards so a single shot shoud do the trick with a fixed full choke. Regarding the load, if you shoot some different loads and shot sizes form your choke you will change your mind as some loads are magic in one gun and suck in the next. I used an A.H Fox SxS made in 1909 for my turkey gun for about 5 years and killed birds from 15 to 45 yards, It will only perform well with remington #5 premier turkey loads yet that same shell in my other guns produces the worst patterns hands down. If you play around you may ad 5 or 10 yards of effective range to your set up.
regards