this is pulled off sigforum.com with all credit going to AZ SIG shooter over there ..
Not too long ago, someone asked for a link to the Army's marksmanship training site and their diagnostic target; the one that shows where rounds strike when you are, say, jerking the trigger. One person mentioned, quite rightly, that this diagnostic tool was for competition shooters using one hand to hold the pistol. Obviously, that person is right! So, I thought that when I went to the range today, I would try to come up with a similar error diagnosing target for a two-hand hold. I shot five rounds each deliberately making various shooting errors on a standard pistol 25 yard bullseye located at ten yards. My pistol for this experiment was my SIG P226 Navy. It appears I was doing so badly that I actually had an offer of assistance from another shooter! It was nice of him to offer. In any event,here are my results.
A: Heeling. Pushing with the heel of the shooting hand as you fire causing the muzzle to climb to the left.
B: Using too little finger on the trigger. This can occur accidentally or when the reach to the trigger is too great for a person's hand size. In essence the gun is shoved to the left by the tip of the trigger finger.
C: Jerk: We all know this one! Yanking on the trigger either to make it shoot faster, to compensate for recoil, or to get a bit more velocity from the round.
D: Increasing the pressure of the grip with just the left (supporting) hand. This seems to twist the gun a bit moving the sights in an arc to the lower left.
E: Increasing the grip with both hands simultaneously. Notice that there is overlap with C, D, and E. I think this is because a jerk on the trigger is also accompanied by a general increase in the grip as well; a tightening of the hands as the index finger yanks the trigger. I think these three "errors" are related.
F: Too much finger on the trigger. If the trigger is too short, or if the grip is not proper, the trigger finger wraps around the trigger and when the trigger is pulled, the tip of the finger applies pressure to the left front edge of the trigger (speaking from the viewpoint of a right handed shooter) drifting the gun to the right. Notice it is a bit lower than it's cousin, too little finger on the trigger at position B. I examined this and I feel it is caused by the over-extended trigger finger pressing on the lower part of the trigger curve so the gun is pulled right as well as a bit down.
One error that is quite common not shown on this target is a general scattering of rounds around the bullseye. This is an insidious error that all the beginning competitve shooters, including myself, had to learn to correct. This is caused when the eye is allowed to drift from the front sight as a string of shots is being fired. The sights should be in focus and the target a bit fuzzy. This should be easy, but it is not! There is a natural tendency to want to see how we are doing as we fire a string of shots. In competition, the bull would be a minimum of 25 yards away and hits could not be seen anyway, but nevertheless, we looked for them! The trouble was, the next shot frequently went off while we were still looking at the target, or when our vision was transitioning back to the sights giving us a bad hit. Now the insidious part. If you do this enough times, especially during a long 2700 point match, your eye gets tired of shifting focus. Your brain then finds a happy compromise and your focus hangs somewhere between your sights and your target while your brain is telling you, "The target is fuzzy, you MUST be looking at the sights!" This was one we worked on constantly in the beginning of our match training; don't underestimate it! If you are watching your sights and applying proper fundamentals, you do not need to look at your target during a string of fire as you KNOW the rounds are where they should be.
Well, there it is! I hope some find this useful.