Learn › Track 04 · Training & analysis

Groups, MPI & sight adjustment

Six shots sit on the card below. Five landed close together, low and left. One went high and right. Before you can decide whether to touch the sights, you need to answer a simple question.

Think first: Tap the point you would call the centre of this group: the point you would want to move into the middle of the target.

The average, not the outline

That average point has a name: the mean point of impact, or MPI. You find it by averaging the left–right position of every shot, then the up–down position.

There is another way people judge a group: draw a circle round all the holes and use its centre. It feels natural, but the circle depends on only two shots, the two furthest apart. Move one flyer and the circle jumps. The MPI uses every shot equally, so one flyer moves it only a little. That makes the MPI the more stable point to adjust from.

The green cross is the MPI of these six shots. The dashed ring passes through the two widest shots; its centre (orange) is dragged toward the flyer.

Two skills, two fixes

A group has two separate properties. Grouping is how tightly the shots cluster. It comes from your technique: hold, alignment and trigger. Centring is where the cluster sits on the card. It comes from the sight setting.

They need different fixes, and the order matters. Fix grouping first. A wide, scattered group has an MPI that wanders from series to series, so clicking the sights to chase it just adds a new error.

Think first: A right-handed shooter fires ten well-called shots. They form a tight group about the size of the 9 ring, sitting high and right of centre. What should change?

  • Technique: the shooter is heeling the grip
  • The sight setting: move the group, keep the technique
  • Both technique and sights at once
  • Nothing: any group that small is fine

Which way to click

The rear sight moves the group. The rule is short: move the rear sight the way you want the group to go. Want the shots higher? Raise the rear sight. Want them further left? Move it left. The front sight stays where it is.

Why does this work? Raising the notch makes you lift the muzzle to bring the front blade back up level with the top of the notch. A muzzle pointing higher sends the pellet higher. The same logic works sideways.

Think first: Your MPI sits 12 mm low. Which way do you move the rear sight?

  • Down, toward the group
  • Up, the way you want the group to go
  • Raise the front sight instead

Try it below. The group starts low and left. Click the rear sight and watch the MPI move toward the middle. Switch on the circle centre to see how a single flyer misleads you.

How many clicks

Each click on the rear sight moves the group by a fixed amount at 10 m. That amount differs between pistols. Pardini, for example, lists 1.8 mm per click for one of its rear sights. Do not trust a number from a manual or a forum. Calibrate your own: shoot a group, move the sight 10 clicks, shoot again and measure how far the MPI moved. Divide by 10.

Think first: Your MPI is 9 mm left of centre. Your sight moves the group 1.8 mm per click. How many clicks right?

When to leave the sights alone

A group of two or three shots tells you almost nothing. Any one of them may have been a poor release. Adjusting after every shot is one of the most common beginner mistakes: you end up chasing your own wobble around the card.

So build the MPI only from well-called shots. If you called a shot as bad (you saw the sights drift or felt the trigger snatch), leave it out. In the first example, if you called the high-right shot as a snatch, the MPI of the other five is the one to adjust from.

Common forum advice: adjust only from the MPI of at least 5 well-called shots. Shooters who reliably call within half a ring may adjust a little sooner. Change one axis at a time, then shoot again to confirm before touching the other.

Think first: Your first two sighters both land low-left in the 8. You called both as good shots. What now?

  • Click up and right straight away
  • Keep shooting until you have at least five well-called shots, then judge the MPI
  • Change your grip and hold to correct it
  • The MPI is the average position of all counted shots. It is steadier than the centre of a circle drawn round the group.
  • Grouping is technique; centring is the sight. Fix grouping first.
  • Move the rear sight the way you want the group to go. Left-handers use the same directions.
  • Clicks needed = distance of the MPI from centre ÷ your click value. Measure your own click value.
  • Adjust only from at least five well-called shots, one axis at a time.

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