What everybody else said.
Actual weights of the two are 43.52 oz for the 5" and 38.59 oz for the tapered barrel 4", for a difference of slightly less than 5 ounces.
I like them both. The MG started out as a 5" full lug, with a new MG barrel from S&W. If I had to choose between the two, I'd probably keep the 5" gun as I prefer the forged parts vs. the MIM parts, though the MG has a slightly smoother action.