Soap,
Please don't go by a rule of thumb or someone saying they can shoot a specific distance. You need to go to the range and find out what YOUR limit is. A bead sight is a very crude way to aim any firearm. If you can't hit a paper plate past 30 yards with it then that's your personal range limit. The only way you will know is to go shoot the thing. I used to hunt with my Rem 870 skeet bbl back when I didn't have a scope for it. I used the middle bead as a sort of back sight and carefully lined it up with the front bead. Helped me to shoot a lot better. HTH and good luck.