I am building a custom Glock 22 upper to put on my Glock 17 lower. The 17 and 22 both use the same frame and internal frame parts for the lower (as far as I can tell). How ever I have been hearing there is a problem with ejection when you put a G22 upper on a G17 lower but no one seams to have a answer on why. Can any one explain what the issue is and what part I would change in the lower to correct it. The goal is to be able to change from a 9mm to a 40 S&W and back to a 9mm at will. Plus the wife put a stop on me BUYING a new gun this year she didnt say any thing about building one......... hehe. Just for the sake of full information I do not have all the parts to assemble the upper yet so I can not try cycling it to see if there is any issues first hand. Im just trying to avoid a possible issue before it becomes a reality.