There are a few 28ga LCS (and others) made by monobloc'ing the orig small bore tubes with new 20ga tubes.
Then simply chambering the 20ga tube with a 28ga chambering reamer.
The 28ga shotshell nearly fits already into the bore of the 20ga tube. The front end of the 28ga chamber is right about at 20ga bore dia. .615 or there about IIRC.
The back end is a bit larger in dia maybe .010/.014,,Shotshell chambers are tapered a bit.
So very little metal is removed from the new 20ga bore dia to do this.
The chambering operation also cuts the 28ga rim recess for you.
Very little metal is removed from the new 20ga bore dia to do this.
Of course you have no forcing cone. None needed as the 28ga wad is emptied into the 20ga bore.
It works well enough but it still doesn't give you the petite 28ga bbls that real ones are.
