There is no weight savings in the shell or the gun when you go to a short magnum. As a matter of fact, you get penalized because some short magnum only holds 3 shells and most other magnums holds 4..
http://www.browning.com/products/cat...llion-firearms
http://www.browning.com/products/cat...item=035002348
http://www.browning.com/products/cat...item=035002349
The gun writers never tells you about that, or the fact that you might pay $80.00 - $100 for a spare clip.