I don't own a Mossberg, but I use a 30-30 Winchester quite a bit and have observed this: The front bead was too small to see quickly enough in the woods. One can say that a fine bead makes for more precise shooting, but I have found that a larger bead is just as precise if used correctly with a 6 0'clock hold.
I slid a tight roll-pin over mine and filled the end with fluorescent paint topped with clear nail-polish. Its larger size is quickly visible in less than ideal conditions now. And no, it does not obscure the target. On paper these should be sighted in for the bullets to strike at he top edge of the bead, (not the center), at the longest range you are willing to shoot, perhaps 150 yards for this type of rifle. Thus the deer or whatever, is always seen touching the front sight, but never obscured by it.
I would never put a scope on this Winchester. However, the addition of a tang-mounted, Lyman peep-sight has made a huge difference in making longer shots good and all shots more quickly. You probably have a tang-safety on the Mossberg, so that would be impractical for you. However, there are receiver-mounted aperture sights that should be a good option for you.
At 62, my eyes are good, but not what they used to be. I use reading glasses now and open sights are a lot more challenging than they used to be. But with a peep sight, it's all good and shoot about as well as my buddy does with a scoped rifle.