Point of Impact
The chart below deals with Point of Impact for shotguns. Point of Impact (POI) is defined loosely as the relationship between the center of a shotgun pattern and a correct point of aim on the shotgun. Point of Impact and Point of aim are closely related. You must use the correct point of aim to determine the POI of your shotgun.
The correct point of aim reference for shotguns can be different depending on your shotgun, your bead arrangement or the type of shooting you are doing. For example:
Single bead shotgun: You would sight from the top of the front bead. This is the point of aim generally for single bead systems across the board: trap, sporting or hunting.
Mid bead and front bead configuration: Found often on target guns. Correct point of aim is usually the top of the "figure 8" which is formed when the front bead is stacked on top of the mid bead visually to the shooter. This is particularly true of trap guns.
Rib itself: Aiming with the flat plane of the rib itself and centering aim with the front bead is sometimes used for point of aim on hunting guns. As a POI reference, this method is less commonly used.
Shooters prefer sometimes desire different POIs for different situations, so our shotguns may have been calibrated by gun design engineers (prior to being manufactured) according to the end use of the gun. Generally our guns are made to be measured either 1) from the figure 8 for trap guns or 2) the top of the front bead for hunting guns. When testing, the shooter shoots at a dot or cross pattern on the center of the paper. The POI percentage is the percent of shot that falls above the dot and below the dot . . . always adding up to 100%. A 50/50 pattern -- with half above and half below -- would be common for many of our hunting guns.
The chart should give you a good idea of how it is calculated and how you can confirm your POI on your shotgun. Detailed instructions are below the chart. You will need:
a safe range to do the testing
several large pieces of paper (about four feet square usually works). An end roll of newsprint paper works well.
something to hold the paper in place (a wooden frame, for example)
a way to measure a 30" circle on the paper (for determining the center of the pattern
a marker to put an aiming dot or "cross hair aiming point" on the paper
a bit of patience
This excellent chart was created by one of our gun experts working at our Arnold, Missouri service facility. The testing procedure is outline below the chart.
Point of Impact Testing
Shotgun P.O.I. Testing Procedure
With our shotgusn all P.O.I. testing is done in our test tunnels at 40 yards. The only exception to the 40 yard test would be the 410. By industry standard the 410 is tested at 25 yards. All guns are shot from a shooting bench using a front and rear rest much the same as what a bench rest shooter would use. A sheet of paper approximately 5’ square is used with a center aiming point of 6 inches.
The shooter will use the sight picture appropriate for the type of shotgun being tested. A flat sight picture is used for Field, Skeet and Sporting Clays and a figure 8 or stacked bead picture for Trap Guns. In all cases a 6 o’clock front sight hold on the target is used. 6 o’clock hold means sight bead held at the 6 o’clock position on the aim point.
The target is shot 3 times, the same as one would do to shoot a 3 shot group with a rifle. The purpose of the 3 shots is to give a denser pattern to work with. After 3 shots the pattern paper is recovered and a template 30 inches in diameter with a center hole is placed on the pattern and moved around to cover the most shot and the center marked. Removing the template, the shooter will measure from the center of the pattern to the center of the aiming pint; up, down, right or left.
With these measurements one can determine where the center of the pattern is in relationship to the aiming point.
Standard Specifications: #38 11-18-10 JJH
The Tech-Term "Point of Impact" is referred to in the following products: