This five shot @ 100 yards was done at Red's Indoor range in Oak Hill TX with my Ruger #1 chambered for .22 Hornet. This range is the only place I seem to be able to shoot groups like this. Maybe it's the fact that I don't have any crosswind to deal with.
What I find peculiar is that the bore sight zero and shooting zero are so far apart in windage adjustment. If I put a new scope on it and bore sight it, by looking through the barrel, and then shoot it, the actual point of impact will be off to the right by a foot or so at 100 yards.
I think one issue is the fact that compared to bolt action's short throw firing pin, this gun has a musket hammer, a heavy hammer with a long throw. I believe this has a lot to do with the fact that my gun's benchrest zero is higher by a couple of inches than the gun's offhand zero. I destroyed a chronograph because of this.
If you are going to shoot this gun offhand, you have to sight it in offhand.
As in all guns with heavy hammers and long lock times, a consistent hold and cheek weld to the stock is super critical, nearly spring air rifle critical, because that big old musket hammer dropping has a reaction that causes the gun to move during hammer fall and how rigid your hold is makes a difference as to how the gun moves during hammer fall. The key is consistent, not rigid, the same every time.
Don't believe me? Put one of these guns on sandbags and put the crosshairs of the scope on the bullseye of a 100 yard target and watch the image in the scope as you dry fire it. You will be amazed at how much the image jumps when the trigger breaks and the hammer falls.
Never did see a factory round that kicked all that hard in the #3 and were IMHO mild in the #1. My favorite load for the #1 is the 330 gr. Lyman #457122, a hollow point bullet that is quite accurate in the #1. I run them right at 1500 FPS. Makes for a pleasant yet rather potent load in the black powder velocity range.