So im confused. The 4506 and the 1006 use the same part number through S&W #201610000. So one would assume they are rated for the same pounds. When I looked at the wolff website the 4506 is rated at 14lbs and the 1006 is rated at 18lbs. I bought one from wolff for the 4506 and it is shorter and does not have the same tension when racked. So whats the deal?