870 mid bead?

[JBK]

Well I'm building a 20 and my funds are depleted after I get my gun smith to drill and tap my receiver for a rail.  I have always shot a bead but was thinking for a little more insurance to add a mid bead.   Anyone done this?  Recommendations on size of the mid bead?  Also I want to get a small front fiber optic front bead as well.  I understand that my point of impact might be off, and if it is I will probably crash some other projects to get my red dot.   Any advice is appreciated!