There's nothing wrong with having a bead sight on your shotgun but if you are in the market for an upgrade without spending the money on a ghost ring setup, you may want to consider this. 
These are listed on Amazon for less than $10 with free shipping if you are a Prime member.
They will work with many different shotguns as you can see below.
I have used this sight during 2 shotgun classes firing in excess of 600 rounds including buckshot and slugs. When I installed it I put blue thread locker on and it has remained tightly secured to the barrel. The fiber optic is installed in such a way that it should not be able to come loose from the base. I have not had any issues with mine.
Here you can see the green fiber optic draws your eye quite well allowing for fast acquisition of targets.
In my opinion, this is a great upgrade to your basic bead sight. It is both high quality and highly effective. For the cost, you can't go wrong.
Well unfortunately after a few shotgun classes, the threaded post sheared off of the fiber optic part of the sight. I bought another one and the same thing happened so I’m going back to the factory brass bead sight. Too bad, I really liked how bright the fiber optic sight was. It just couldn’t withstand much use.