According to the summary of "finding out for myself Part VIII", they removed over 1/2 pound from a pair of LC Smith barrels

http://www.shotgunworld.com/bbs/viewtopic.php?f=13&t=259371&start=40

I also have a hammer gun that was significantly lightened by honing from 12 gauge to 10 gauge dimensions while retaining ample wall thickness. Don't know what the original weighed, but it must have been a similar weight reduction to the LC Smith described above.