It all depends on you and the gun. What type of gun are you talking about?

For a smoothbore you would need rifled/foster type slugs and a Modified or more open choke, not a full. A full might work, but I doubt accuracy would be too great.

Range will depend on how well you shoot and how well the gun likes the particular slugs you are using. In most cases figure on around 60-75 yards or so with a smoothbore. Sometimes you can get more, sometimes it's less. I figure max range is where the group opens up to about 5 inches or so. As far as ballistics most 12 and 20 ga slugs be it rifled or sabot have what it takes to kill deer out to 100 yards, some beyond that if you can hit what you are aiming at.

My mossberg 500 with a smoothbore was good for about 65 yards. My A-5 stalker with a 21 inch smoothbore is good to around 100 yards. Both had fiber optic open sights.

A rifled barrel should get you out to 100 yards pretty easily.

Paul