First of all the dead on is correct as is. The target is supposed to be fuzzy and the sights clear just like the pictures show. Or should. If you sight properly then the bullets will impact where they are supposed to without seeing the tiny bullseye. That's the way it works and always has.
If a shooter does what is shown in the pictures properly then they will hit properly using either type of shooting.
For some 6 o'clock works well, but this is not normally technique used for a defense handgun. Expecting very tiny little groups to be in a target with pistols and revolvers that are not target grade is ludicrous at best.
Dead on is normally taught for defense weapons.
One does shoot the best they can, but expecting one ragged hole or target quality is again not consistent with reality. Guns that are target grade normally have ammo and firearms designed for more consistant hitting the same spot in very tight little groups. There are exceptions.
Engineering is more precise ballisitically for the ammo and the fit and function of the target pieces used to do this with. Tolerances are tight all across the board.The amount of research and developement that goes into target grade guns is a lot more effort than what goes into defense pistols or revolvers.
For defense accuracy is needed as well. However the precision with which shots can be placed is not on par realistically with target grade guns. Otherwise target grade guns are all one could or would buy. Expense would put this out of a majority of civilians reach.
Not under adrenaline dump,extreme stress and duress, fine motor skill loss, heart pounding, fight or flight situations is one going to realistically calmly shoot the human target/s as if on picnic and out for relaxation.
Special units use target grade pistols and revolvers because of the need to be more precise with thier shots than civilians. They are trained to a high degree most civilians will never match or be able to for expense or reasons of time. The specail unit operators learn to do this under stress, shoot amounts of ammo at prodigious rates, train incessantly,and have budgets to allow for this. Civilians normally don't have access to this sort of thing.
http://www.taurusarmed.net/forums/index.php?topic=2418.0
The above link deals with some of the vagaries that go into shooting defense sidearms.
Expense,harsh operating conditions, harsh enviroments, reliable fit and function,as well as humans being bigger targets, mean that gun makers have to compromise and reach a level of ability for the gun to deliver what is normally accepted "combat accuracy" at reasonable combat ranges for sidearms. Gun makers have done that.
POI will very if a 6 o'clock hold is used vs. a dead on sight picture.Depends on how you zero the gun or shoot it as well.
Target shooters are well served by the 6 o'clock hold. Defense shooters are not.
Most shooting instructors or schools use the dead on for defense teaching. Not written in stone.
There are many factors and vagaries that have been gone over again and again where shooters were having troubles.
Could be the culmination of a number of things and we staff and members are not there to see each person on a case by case basis shoot. Nor the conditions, nor do we see the stance ,grip,or trigger follow through. wish we could, but realsitcally can't.
So we advise the best we can covering practically ALL the factors we can.Whether operator error or inexperience,real gun troubles, intangibles we cannot know about, or a combination of any of the above described factors,we can only surmise what is going on.
Even bullet weight, kind of ammo,brand of ammo, or even what batch are factors that come into play here.
Then there is the fact the fixed sighted guns,especially compact or sub-compacts, are hard to regulate the sight on. Doesn't matter what brand,make ,or model by any company, this is true for all of them. Many of the factors in the link come into play here.So do others too numerous to mention.
With all that said, the companies do the best they can with what they have.
Fixed sighted guns are going to shoot high,low,left right. Even the sights on alike samples will not have the same POI. These are massed produced non-target guns at price rates the regular buying public can afford. Some more expensive than others. High price is not and indicator of quality. Many like to think so but I digress.
Ever since firearms were invented fixed sights rarely hit perfectly to point of aim. Too many factors and vagaries enter in.
If one has a fixed sighted gun one has to take the time to experiment to find the best combo of ammo for fit,function,reliability, and for accuracy. POI does figure in, but is not the most important factor. Other wise hardball or target ammo of any shape would do.
One gets to the nearest POI that is as close to dead center as possible, but for many reasons already stated that may not be realistic. One will have to learn where to put the sights for dead center hits and then learn to live with that.
Experimenting with the factors described above takes time,dedication and experience. Each trip to the range need to have a goal other than just putting ammo downrange or shooting tight groups. There are a lot of factors in defense shooting that need to be addressed and kept up with to be proficient.
All this is covered somehwere within the forums here and gets discussed time and time again.
So yes, it is possible the guns shoot low.It is also operator usage and the many factors in HOW they go about shooting that come into play. This as well as the factors of the gun,ammo,and enviroment. Even humidity,cold, and heat play into this.
There are a plethora of new shooters here at this forum. New even to the type of guns or gun they shoot. Have to learn the vagaries and performance abilities of gun ammo, and the person. This holds true for even those who shoot regularly and have experience with most or all types of firearms. Even the old vet shooters have things to learn and find out. We never stop learning nor gaining experience.
So coming in here and picking on the example pictures when there are so many factors seems silly to a degree. There may be better pictures and examples describing this. There might not be too.
Shooting low can be the gun... and it can be the shooter.. or the ammo, or other factors. Combinations of factors also as has been seen.
Same goes for shooting too high,low, or somewhere in between.
http://www.taurusarmed.net/forums/index.php?topic=2872.msg21251#msg21251
Drummin_man62 had the right idea for those of us who are having sight issues and it is the user for the most part. Even us so called shooting vets can have an off day or develop bad habits. Hard to unlearn, too.
There are a lot of things to consider.
Mentoring by another qualified individual who can use constructive criticism is a good way to help get to proficiency. Then staying at that level of proficiency is another thing.
Sights can be changed if need be and replaced by others. Then there are those of us who make due and make minor corrections with our fixed sights to hit the center.
Did this with revolvers and learned where,even at long range (100-200 yards) where to hold to get dead center hits with certain specimens of handgun. Not all, just a few.
This with fixed sights.
It is realistic to expect to hit the general target as well as we can. Perfection and total precision will not happen for the most part with combat handguns. Some can get to that level. Some combat handguns are that precise, but are the exception rather than the rule. They will not necessarily be the majority.
If you see the target clearly the sight very well may be too fuzzy for good work. Even if you can't see the tiny bullseye, the bullets will hit the mark.
This also depends on range and realistic targets for realistic work for that particular gun.
Members and staff try to provide adequate info and advice. I think they do that at a very competent level.
Figured this all needed to be said or covered.
There are exceptions to this. For example, there are some of us who have regular revolvers or pistols that shoot groups that are up there with target grade quality sidearms. Cherish those dearly if you have pistols or revolvers that can one hole for many shots it or shoot ragged little groups at medium to long range.