Offhand slow fire is usually everyone's problem area, and 99% of the time the problems are self-induced. The first issue is that everyone holds the firearm, which can weigh up to almost 4 pounds depending on the model when it's loaded out in front of them while they try to minimize the wobble area. This has the opposite effect. The longer you hold it up and out in front of you, the larger the wobble area will get. That results in you jerking the trigger trying to get the round off when the sights are crossing the center, or where you want the bullet to go. All this does is cause the sight alignment to move off and sends the bullet off into neverland.
The next issue is breath control. If you don't hold your breath when shooting, you induce movement, which causes sighting errors. When shooting slow fire you are to take in a deep breath or two, let it out to where you feel comfortable, align the sights, while keeping the sights aligned, front sight centered and clear in the rear and pointing at the target using a consistent point of aim while pressing the trigger. It is imperative that the front sight is clear in your vision. The eye can focus only on one point at a time. This needs to be the front sight. The rear sight will be a bit fuzzy, so will the target., This is normal and the way things should be.
In general when shooting bullseye there are two different holds used, center of mass and the 6 O'clock. Personally, I much prefer the center of mass. "Why?" you ask. This is because you are using the entire aiming black of the target as your point of aim, thus keeping your wobble area within the aiming black. If the sights are aligned and anywhere in the black, when the gun goes off the bullet is going to go into the black.
If you are using the 6 O'clock hold, you are trying to get the sights to align on a miniscule area right at the bottom center of the black. This causes you to wait until the sights are at the bottom of the target, and you have a tendency to jerk the trigger trying to get the gun to fire when the sights cross the bottom center of the aiming black.
There are two things that cause issues here. They are called reaction time and lock time. Reaction time is the time when, your brain tells your finger to pull the trigger, and it actually happens. Lock time is the time from when you actually pull the trigger, releasing the firing pin, which in turn hits the primer, which then ignites the powder and sends the the bullet down the barrel and out the muzzle toward the target. During this time the gun is in , constsant motion, which results in the bullet leaving the barrel long after you anticipate pulling the trigger and it actually happens. During this time the bullet will now leave the barrel when you are not aligned, resulting in a miss, or at least not hitting where you intended.
OK, lets go through the right way to do it. Essentially, you have one minute for each shot which is actually a very long time. You start out in the rest position, your hand or if shooting two handed both hands gripping the firearm in a good single or two hand grip and down resting on the bench in front of you or simply down in front of you in a relaxed position. You focus on the target while breathing in and out, I use deep breaths to saturate the lungs with oxygen.
When it's time to shoot, I take in a deep breath, let is out to the point where it is comfortable, I hold the breath and raise the firearm, aiming toward the target. I align the sights on the center of the target, minimize the wobble, and begin a trigger press while keeping the sights aligned and the wobble minimized. The trigger press is just that, a slow and gentle rearward pressure on the trigger until the gun goes off, while concentrating on the sight alignment. The gun going off should come as a surprise and you should be able to note where the sights were pointing when the gun went off. This is what is called by professionals as, "Calling the shot."
Once the trigger releases, it sets off the firing sequence. If you keep the sights aligned and follow through the bullet will then be on it's way to wherever the sights were aligned when the bullet left the barrel.
Now for some things to practice. Use an unloaded firearm that is safe for dry fire. It will be somewhat lighter than a loaded firearm, and that is OK. Take the firearm and put it in a good one or two hand grip. I use a digital clock as the target across the room from where I am. The clock needs to show the passage of time in seconds, minutes and hours. Take a breath, and let it out as described above. Pull up the firearm into a good standing position aiming at the target and noting the seconds. While aligning the sights on the clock, watching the seconds tick by note how the point of aim starts to increase as well as how the digits on the clock start to blur. The wobble will start to increase and the second numbers will start to blur after about 5 to 7 seconds. Try holding the position while sighting as long as you can. You will note the wobble area increase and the target continue to blur as long as you hold your breath. If you take a breath at that point, the vision will quickly return, but the wobble will continue to increase.
Practice dry firing using the following little chant. "Breathe in, breathe out, hold, bring handgun up, aim, and press the trigger. You are attempting to get the gun to fire within 5 seconds or less from when you held your breath. Once the handgun fires, go back to the rest position and start the sequence over. Take your time, you have a minute per shot time limit. That will seem like forever, and it is.
Timed and rapid fire are much easier.