OH MY GOD!!!
What a thread! The extremes of misunderstanding and expertise all in one place!
RULE - FACT - REALITY: No matter what some half-brained S&W customer disservice idiot tells you over the phone or some well-meaning but hopelessly uninformed forum participant writes, THESE ARE SOME ACTUAL RULES FOR SHIELD FACTORY SIGHT ADJUSTMENTS:
1. Looking at gun from REAR (which is the shooter's view), always move the REAR sight in the direction you want the group to move and always move the FRONT sight in the OPPOSITE direction you want the group to move.
2. ALL Shield REAR sights are NOT MEANT TO BE ADJUSTED and that's why they are so wide as to FILL the dovetail! READ YOUR DAMNED MANUALS before you start giving bad advice or ruining the integrity of your gun.
3. ALL Shield FRONT sights ARE adjustable. That's why there is so much room in the front dovetail compared to the width of the sight base.
4. ALL Shields are designed to be sighted or zeroed at 25 YARDS!!! That's 75 FEET!!! NOT 5 feet or 6 FEET or 7 YARDS or anything else!!! Therefore, anyone who adjusts their sights at closer distances is destroying the integrity of their gun (or maybe has a unique, individual reason for doing so).
5. All commercially manufactured American ammo for 9mm, 40S&W and 45ACP handguns is specified at the SAME 25 YARDS!!! That may be your clue as to why all handgun sights are designed to be zeroed at 25 YARDS...You Think???
6. And, what I think is CRITICALLY important about all sight adjustments by a shooter on ANY gun, is: if you have to move your sights more than a few thousandths of an inch to correct group placement EITHER it's YOU or you have a bad gun or ammo!
7. Last, the most important control factor in adjusting handgun sights is to shoot at 25 yards from a STABLE and REPEATABLE bench rest!!! No human hands can provide that (except for maybe Jerry Miculek, who none of us are). A Ransom Rest is the ONLY such device I am familiar with that is totally stable and provides for absolute repeatability from shot to shot so you REALLY know where the gun/ammo is shooting. ALL OTHER DEVISES introduce an element of error, especially repeatability error, so sandbags, bench rests and Bubba will provide you with inconclusive results. Not many of us could afford or justify a Ransom Rest so we do the best we can and hope for the best, I know.
Now, as to S&W's lousy quality control, sloppy assembly, shipment of defective and dysfunctional Shields, and idiotic customer disservice, just read some of the threads in this forum for the past 5 years and you'll have no doubt that it happens.
Could you have a bad Shield 40? Yes. Could it be your own shooter-induced error? Yes. How can you tell? As has been posted so many times here and elsewhere, let a more experienced shooter fire your Shield and see what happens. In MOST cases, the gun will group much differently than when you fire it. What do you do then? PRACTICE - PRACTICE - PRACTICE.
Now, it would be unfair and just plain wrong for me to imply that no shooter is qualified to adjust his sights. Many are. But, a complete understanding of the Basic Rules for Sight Adjustment and your operator's manual is important before you start or you'll just make matters worse.
If all else fails, and only then, send it back to the factory or find a highly qualified gunsmith to examine your Shield. (Is there any such thing as a highly-qualified gunsmith any more? Most are just parts changers nowadays.)
My GOD. Forgive me for my early morning, 3 cups of coffee rant, but threads like this suggest to me that too many new gun owners are getting their hands on too many new guns while lacking BASIC understanding of gun ownership, operation and maintenance.
Sorry if I offended anyone but that's life. Grow a set.
