If I really try I can group in 4-6" with my bow at 50 yrds which is about as offhand as it gets. Seems most of the time I can find a rest for any rifle hunting whether its a tree, fence post, edge of the stand or the bipod. this is my preffered method as I really don't like tracking and like to make a good shot. If I am close enough that I need a quick shot either the game is running which I generally don't shoot at, or its so close you couldn't miss. However most of my big game shooting with a rifle is in the 100-250 yrd range and you usually have some time to make the shot and get in a better position than freehand standing.
I am reading a book by Jack O Conner and he seems to be known as a great sportsman. One of the things he writes about is a lot of off hand shots at big game either at some distance or while they are running. I am really surprised by the shots he and his buddies took and the number of times they missed on shot 1 & 2, connected on #3, missed number 4 and then connected again on #5. It seems in 1/2 of the stories he empties the clip. I can't judge this as good or bad but he was someone who was supposed to be a great hunter and he missed alot of shots too. Shows what adrenalin and freehand shots will do.
Where would I find some good gong material? I would like to make 6" and 12" to drag out to the range with me. Would be fun to play with.