[1] Do you mean if I didn't have any feed out for them ever? Then they would be forced to go on walkabout to find food?
Are your chickens running around in a forest? Mine seem to feel safer in forest-like areas and seem to go further once they are in an area like that, but they still don't go more than 100 yards away from their house and never 400 yards away into the woods.
[1] If you were hungry and with no expectation of being fed would you go on a 1/2 mile walkabout for food?
Yes, my chickens like the woods and have access to a wooded area.
Can be expected to and doing something is mutually exclusive. Free Range means just that. It is analogous to the open range in Pioneer days when everyone allowed their Hogs, Horses, Cows, Goats, Sheep, and poultry to run wild and feed everywhere except where crops were planted. These areas were enclosed by rail fences to keep livestock out. Later barbwire replaced the split rail fences and later still the farm animals were the ones fenced in and crop land became the new open range. So to me "free range" is just what it says, free, open, unlimited, and unfettered. However a meat bird isn't going far. He would run off too much weight, the exercise would stress him and his muscles would become tough and fibrous, Not Good Eats.
A diminutive breed or bantam can be expected to stay closer to home.
I have pointed out many times that strong and direct Sun is deadly to a chicken. Once we remember that our domestic chicken is nothing but a sub-species of the Red or Gray
Jungle Fowl can we begin to see why your chickens prefer to forage in a wooded area with plenty of shade.
By feeding your birds you reduce their free range tendencies. Chickens unlike humans only work as hard as is necessary to feed themselves. Besides in a true free range situation foraging is dangerous work with predators lurking behind if not in every tree. Also the more beaks there are to feed in a given area, the further you can expect your chickens to travel to fill their craws.
400 yards is less than 1/4 of a mile from a
central location.