WOO HOOO! ! ! ! Apparently I'm not as blind as I thought ! ! ! ! !
Not tooting my own horn.... well, I guess I am but I'm not fibbing either.
At my clubs 20 yard indoor range I often shoot a 1 to 1.25 inch group from a prone non rested position. The rifle being a Henry H001 or my rather old and crusty Remington Model 6 single shot with basic iron sights. If I use a rest for the front stock I can easily get under 1 inch. This from the guy with 60 year old "old guy eyeballs" and struggling to hold the rifle steady....
Translating that out to 50 yards and I'm still in the running....
For center fire from a front rest I can generally manage 3.5 to 4 inch groups at 100 yards. The odd time I'll be all twitchy and it'll be a lot bigger but generally I can see well enough to keep it within the 4 inches. Rifles in this case being my Marlin 336 or Win 94 or either of my Mosins IF I'm using something other than the poor milsurp junk.
I never really thought that this was all that great since I often read folks saying that they get 1.5 to 2 inch groups using rifles with plain iron sights such as milsurp rifles, Winchester 94's and the like. So I never would have thought I was really in the running at all.
When I was sighting in my Lyman Great Plains flinter it also shocked me by matching this 4 inch "eyeball limit" for grouping.
So all in all I've got 4"/100yard eyes it seems. With target peeps I find I can cut this down by a bit to probably more like 2.5 to 3 inches at 100.
For those of us with "old guy eye'tis" do NOT discount the value of a good high contrast target. I put up with poor targets and blobs of red spray paint for a long time. I finally broke down and bought some 8 and 12 inch "Shoot N'C" targets for my 100 yard and out farther shooting. I cannot believe the difference. It's like I got back 50% of my lost vision. For scopes it really doesn't matter that much other than at the extremes. But for unaided Mk I eyeballs used with old plain irons the sharp black on white of these targets makes the contrast really jump. And the big spatter patterns sure do make it easy to see the hits through a scope or even decent binos.