Is it recommended to use a scope on a shotgun if you're using slugs at 30-50 yards? (open field shot) I'd prefer not to use a scope since I also intend to use the shotgun for home defense. ...a laser would be ideal, but I heard they may not be legal. ...not sure why.

a scope is not needed but for me it gives better confidence and refined view of shot placement even at 30 yards. theres nothing like having steady cross hairs from a scope on game especially as your eyes get older.maybe pick up a seperate 18.5 inch barrel for home defense if its a pump or semi.

The scope is not needed. As said previously it depends on your vision.

I agree, nothing like the confidence you get when aiming with a scope.

i personally would not scope a shotgun if my shots were only gonna be up to 50 yards. i would upgrade the sights to fiber optic if your shotgun did not come with them.

I set up my Remington 1100 in 12 gauge for hunting at Fort Knox several years ago...(Fort Knox does not allow you to have a "spare" gun in the truck...actually you are only allowed to have 10 shells with you)...

1. Remington fully rifled barrel with "open" rifle sights.
2. Drilled and tapped the receiver for a full length Weaver base.
3. Mounted a 3-9X40 scope in a QR Quad-lok ring

This gives me a scope for shooting out to 150 yards or so, but also open sights in case the scope fails, the weather freezes the scope over, etc.

I have a scope on my 870's cantilever barrel and one on my H&R USH that I just picked up.
You might want to look at a holo site type red dot. Then you could still use it for both hunting and home defense.
Also, lasers are not legal in Ohio for hunting. Not sure about other states.

I think the idea is that this technology provides the hunter with an un-sporting advantage.

For 30-50 yards in the open, put a good receiver sight on the gun. Like the Williams Foolproof!