I have both a GG and an older 1895. Both are loud (same load), but the GG is MUCH louder, yes it is ported. I hunt Elk in NW CO, and I take the GG over the original 1895. It is handier, swings quicker and has more power then is really needed for Elk. I load 350gr Hornady FP (brought out for the 450 Marlin) and you hit an Elk with them with a max load and it does knock them off their feet. BTW both shoot that 350 at or under MOA! But they do kick!
Currently I am trying to work with cast 430GC. Can't get the accuracy I want yet, but I won't give up until I do!
Both bores are at 457+ with no speed bumps.
Any one that wants a big bore can not go wrong with the GG weither with factory or handloads. WW Supreme 300 part, shoots real good out of both but not as tight as my hand loads.