I'm just a beginner adult and I can group at about a 2 foot diameter at 40 yards shooting every 15 seconds. There's someone at the range I've seen who shoots at about her speed (every 2 seconds) with a primitive bow (no recurve in it) that I think he made himself and groups about a 6 inch diameter at 40 yards -- quite a sight to see!
I love your handle name, GrendelKhan -- _Grendel_ issues around #40 are among my favorite of all comics, definitely in my top 20.
I've been waiting for the time when there's enough data about other solar systems to see if it also applies to them. Right now while we do have some data about other solar systems, we don't have enough about each (I think the most we know so far is 3 planets around a given star, though I might be out-of-date).
Those are pretty good books, particularly the first. I've read them all twice.
I will say that his best works are _Jailbird_ (probably his most "serious" work) and _Slapstick_, though there's a place in my heart for the flawed _Happy Birthday, Wanda June_ (though you should skip the movie version).
I've also read _Venus on the Half-Shell_ by Kilgore Trout, but the best I can say of it is that it's "different". Not recommended except for completionists.
* In actuality, even this isn't right, as I still haven't read _The Sirens of Titan_. I suppose I'm just a congenital liar when it comes to my proportion of Vonnegut novels read. Could that really be genetic?