Ultimate group size on paper is the product of two inputs: the inherent "accuracy" (i.e., repeatability) of the pistol (this is sometimes known as "machine accuracy"), and the skill of the shooter (which means the ability of the shooter to have trigger let off occur exactly when the sights are perfectly aligned with the target).
In a perfect word, machine accuracy would be 100%. That is, a pistol firmly anchored in a Ransom rest that is itself firmly anchored to the bench should put all the shots into one hole. This, of course, doesn't happen. A number of factors are at work, but with autos the dominant factor is an unavoidable variation in lockup, which means a variability in the exact alignment of the barrel to the slide (sight alignment) or the frame (rest alignment). The second most important factor is ammunition consistency, both as to velocity and headspace.
Based on experience, I would estimate that the best machine accuracy you'll find for a good 9mm auto using good ammo is about 2-3 inches at 50 yards.
Now for the shooter. In a perfect world, the shooter would be able to hold the pistol as steadily as the machine rest, and his visual accuity would be such that he could align the sights to the target exactly the same way each time. 'Tain't a perfect world.
In the real world, the gun wanders across the face of the target. For good shooters, the radius of the wander is smaller than for shooters who are still learning. What do you do? An MBA candidate might respond that the thing to do is wait until the sights are wandering right to the middle of the target and then snap the shot at the moment of perfect alignment. Unfortunately, MBA candidates are poor shots, for this is the worst thing you can do. What you should have been instructed to do is allow the gun to wander and slowly squeeze the trigger so that the moment of discharge is actually a bit of a surprise. This means, of course, that at the moment of discharge the pistol could be "aimed" anywhere within the shooter's wander radius. What happens is that after an awful lot of practice (and ammo expended), you wander radius will get smaller and smaller until you reach the peak level of "shooter accuracy" that you will ever obtain.
There are a bunch of other factors affecting shooter accuracy. One is barrel length, or, more precisely, sight radius length. The longer the sight radius, the more precise (in terms of subtended angle) one's ability to discern proper sight alignment -- all other factors held equal. Then there is visual accuity itself. Finally, there are a bunch of technique factors.
Again, based on experience, I would estimate the wander radius for a reasonably experienced shooter with a good 9mm auto to be on the order of 4-8 inches at 50 yards.
As a result, if you can consistently shoot 5-shot groups into a 6-inch group at 50 yards, I'm impressed.
![[thinking]](/xen/styles/default/xenforo/smilies.vb/010.gif "Thinking [thinking]")
)with excellent bullseye equipment (i.e. not me), but with a defensive pistol, forget it.![[bow]](/xen/styles/default/xenforo/smilies.vb/027.gif "Bow [bow]")
![[laugh]](/xen/styles/default/xenforo/smilies.vb/012.gif "Laugh [laugh]")
![[wink]](/xen/styles/default/xenforo/smilies.vb/002.gif "Wink [wink]")
