I've heard and read this for decades:
The X-10 rings of a 1000 yard LR target is ~20 inches across, so in theory a 2 MOA rifle should be capable of cleaning it.
True, but only when shot in an indoor range where there are absolutely no wind currents and the rifle's held by a 3-point supported free recoiling cradle in a machine rest.
In the real world, here's what happens.
If one gets a rifle and ammo that shoots no worse than 5/8 MOA at 1000 when machine-rest tested, that's a good start for the first one-third of the game.
We all have a beating heart to keep our eyes working well but that blood swelling our muscles attached to our 3-point suspension system slung up in prone (both elbows and one side of the rib cage) tend to wiggle it. That bounces our holding area on the target. The best folks shooting top scores will keep that bounce or wobble area inside a 5/8 MOA circle.
After taking three deep breaths and exhaling them (hyperventilating) to where half the last one's let out, we hold that wobble area while "thinkiing" the trigger back to fire the shot; with training we can fire that shot decently inside that wobble area. The round fires and the bullet starts down the barrel. So all of this adds another 3/8 to 1/2 MOA to what the rifle and ammo does.
Now we gotta hold perfectly still until the bullet leaves the barrel. Meanwhile, our body's not gonna be holding that rifle exactly the same way for each shot. The resistance it presents to the recoiling rifle ends up making the muzzle point to different places for each shot. And this adds another 3/8 to 1/2 MOA to what the system's accuracy and holding errors add up to.
Few of us can judge wind to no worse than about 1/2 to 3/4 MOA perfection. And we won't see those subtle wind currents that ever so slightly change the wrinkling mirage (heat waves) moving across our scope's field of view. This can make another 1/2 MOA or more addition to the ones mentioned earlier.
So we throw parties if we keep all our shots with a 5/8 MOA rifle and ammo package inside 2-1/2 MOA at 1000 yards. The 10-ring's 20 inches. Inside it's the X-ring at 10 inches. And the 30-inch 9-ring encircles them. They're centered in the 44-inch black 8-ring that's the aiming bullseye.
20-shot scope sight record's 200-19X.
20-shot metallic sight record's 200-17-X. Most matches are won with a 198-14X or better in average range conditions.