To someone who has shot more than enough for a lifetime, I can tell you that this is the most annoying and misplaced word in the gun community. Accuracy is not defined by where the bullet lands in relation to where you wish it would go. Accuracy is about the consistency of impact at a predetermined distance, regardless of the sights. We are of course talking about the gun itself and not how the sights are zeroed to the guns POI at such and such distance. There is almost no way in hell that you as a human being can decide or evaluate any gun's accuracy with any consistency or precision. As I have always said, as long as it has rifling, it should be accurate. Barring having issues with twist rate and manufacturing issues, every gun is accurate...relatively speaking. Still though, they are more accurate than we could ever be.
Okay, let's look at the discussion this way. Imagine that the gun is placed in a vice that eliminates all movement in a perfect world. Also the ammo is loaded to absolute perfection and consistency. Every round is made perfect and even the environment is perfect. At this point we have eliminated all other variables except the rifling. Now we will load 5 rounds in the pistol one at a time and fire it at whatever range, whether it is at 25 yards or 50 yards. Not counting the POI to POA, don't you think that the gun will perform quite consistently? Barrels and their rifling are made of steels and alloys that are not going to shift in size just due to the pressure and the gun itself is not going to change enough to throw the shots off of an appropriate group.
Now let us evaluate the variables that we removed from the equation. First let's look at the weather. We all should be on the same page that the environment our guns and ammo are in will dictate their overall performance. Heat will typically make our ammo burn faster and perform hotter. The atmosphere can even affect the ease with which the bullet can travel through the air. Then of course there is good old wind, which can blow your bullet one way or another. There are other variables too that can bring a huge gang of micro-issues to the table, just on the environmental standpoint. With these environmental variables being inconsistent, how are you going to judge accuracy with any competency? Hold onto your seats, because this is just one part.
Next let us look at our ammo, which is far from perfect. Let's look at how ammo works first. The amount of powder, how it is laid in the cartridge when it ignites, how far down the bullet is in the cartridge, how hot the primer burns, and all this other good scientific stuff will be the reason that your ammo will never be consistent except in a perfect world. You can weigh out every charge and make your primers as best you can, and make your bullets, but you still have no say in how the priming compound works when it goes off. Nor do you have control over how fast the powder burns in every shot. Add environmental disturbances as simple as the chamber being previously fired and hot, with the barrel having more fouling, and you got yourself a recipe for reality.
Now let us look at the last variable, which is the one that causes most of the issues. The platform in which the pistol is being fired is the one that determines where the rounds impact, relative to the previous factors of course. You as a human being are flawed and imperfect, with a side of arrogance. Your muscles responsible for holding the pistol, even on a rest, are never going to be consistent. Also let us add in the fact that our very heartbeat causes a sway, never allowing us to be stable enough for a perfect shot, unless we lower our BPM to a level near death. Now let us add in the fact that our eye sight is incapable of accurately calculating perfect center on a front sight post. And for this, let us just say that it is roughly impacting right in the center of the front sight post at 25 meters. With that, we also need to realize that it isn't quite in the realm of reality to expect to be able to line up the rear sights with the front perfectly. The right eye relief and space on either side of the front sight is also something we will never be able to perfectly align with any consistency.
Now for the last and probably the most important variable to remember, your brain. The human brain has calculating limits and limits on what it can register and respond to. Consciousness of body movement and response to changes are hard when the human eye barely pics up pistol recoil. Our emotional center can have an affect on whether we jerk the trigger, or dip the muzzle down/up in fear of the repercussions of the recoil and not being ready for it. These are normal reactions at the last minute in response to recoil, or at least the anticipation of it. Oh, but wait because here is the best part. When you squeeze, pull, or do whatever with the trigger, you will consciously or unconsciously loosen or tighten your grip, causing deviation and change to all the above variables that you thought you had verified.
With these emotions and responses, and all the previous checks and verified calculations in complete disarray, being left with only faith and chance that you will hit where you intended to. Now add in your ammo variable and your environmental variable. In total there are three variables that will screw up the faintest chance for you to evaluate a pistols' ACCURACY. The only thing you can ACCURATELY say is that you can shoot the pistol accurately. The best thing you can do to get more accurate is practice, practice, and practice some more.