Glock Ballistics Puzzle

[Cbreeze]

I shoot my Glock with its fixed factory sights at 7 yards, typically. At that distance, for POA = POI, I have to hold high just a smidgen. My front sight is therefore not lined up with the front sight posts, but is just a little above. Put differently, my Glock shoots low -- and I've seen many complaints about Glocks shooting low and left.

I understand that Glocks are factory zeroed at 25 yards, I assume because the LEOs qualify there for reasons that no one has ever figured out.

Is it possible that the reason it shoots a little low at 7 yards is because the arc of the bullet has not yet hit the first point where the sights cross the arc (second point where sights cross the arc is at 25 yards)? How would I determine the distance to that first cross over point? (Think about ARs and the zero at 25 meters equal to battle zero at 300 meters -- two cross over points, at 25 meters and 300 meters.)

 

[Kinbote]

Shooting low and left is usually from jerking the trigger or squeezing the other fingers of your hand. It's likely to be more pronounced when shooting a Glock due to the trigger they have.

Police only qualify out to 25yds nowadays, rather than up to 50, because they no longer issue the .357 magnum Colts and SW's, which could hit targets at that range, given a bit of training. Many of the new officers they are recruiting are not exactly shooters, and the issue weapons are usually Glocks or similar semi-autos which are not as good for long range precision shooting. Most shootings are at short range anyway, so it is simpler to do the easy thing and not try to train to the limit of the weapon.

You didn't say what caliber and bullet weight you were using, so I can't tell you what the ballistic trajectory is.

 

[Cbreeze]

Shooting Federal American Eagle 9 mm 115 grain FMJ. But the question I have is how to figure out the trajectory . . .

Yes, I've heard this about trigger jerk and the Glock trigger and I'm not fully persuaded. If every other manufacturer has been able to make a gun that is not susceptible to this supposed jerk, then why doesn't Glock do it? (For my own part, I know that my grip on the Glock is funky because it doesn't fit my hand, so I have no dog in that fight.)

I wonder why police qualify to 25 yards since most of their shots are 7 yards and less, in low light, and without the use of sights. And then they miss about 50% of these since this is not what was emphasized in training/qual . . .

 

[davsco]

But the question I have is how to figure out the trajectory . . .

sure you can find ballistics/trajectory info on the web, also some ammo boxes list it. but this is generic stuff for a generic gun. just set up targets at 5 - 50 yards, maybe in 5 - 10 yard increments, and see where your impact is at each distance. then you know for sure what your gun does and can aim accordingly.

 

[Kinbote]

Every trigger, even one on the very best top-end 1911, is susceptible to being jerked. A trigger that has a lighter pull weight or less overtravel, or a cleaner break, is simply less susceptible, so it isn't something that only applies to Glocks. A Glock trigger generally has a heavier pull than some semi-autos and the trigger doesn't break as cleanly as others, so people using it are a bit more likely to jerk it. The unwieldy nature of the Glock grip magnifies the problem of jerk and causes more difficulty with getting a good firing position, especially for those with smaller hands. None of those problems are insurmountable, especially if you devote a bit of time to practice and dry-firing.

If the gun doesn't fit you well, you might want to try a different handgun. A good fit will help you greatly.

http://www.chuckhawks.com/handgun_trajectory_table.htm

I don't have any specific info on 9mm, but that cartridge, and especially that bullet weight, is pretty flat-shooting. The chart above says it has a max point blank range of 107 yds, the distance at which it will drop 3" below the line of sight. In response to your original question, I don't think any handgun rounds have a ballistic arc so short as to rise at 7yds and begin dropping at 25yds, the way a 5.56 does 25/300m. With your 9mm, you should be able to hold dead on and hit within 3" out to 100yds or so.

I'm not sure what the average inherent level of accuracy from a Glock is, but I'd assume 3-4" groups at 25 yds would be common. You should be able to keep all your rounds touching at 7yds, so that might be a suitable goal for you to work towards, then move back to 10, 15 and then 25yds. Always try to improve your skill, don't limit yourself to 7yds.

Police(and everyone else) should be using their sights in almost all but contact situations. Failure to do so reflects a lack of training. Most shots are at close range, but not all, and so it is a good idea to be able to shoot with confidence to 25yds, or 50 or 100. The amount of training it requires for that level of skill is impractical for police academies, so it is not going to be incorporated into curriculum any time soon.

 

[rob-cubed]

My two Glocks are right at POI/POA at around 15 yards. I haven't shot them at closer ranges, but the sights are designed to cheat the bullet higher and account for drop at 25 or 30 yards.

What you should not get in the habit of doing is changing the sight picture, keep the sights in the same plane and raise or lower POA as needed to compensate for POI.

 

[Cbreeze]

OK . . I won't cheat the sights You've convinced me that it's not trajectory at that distance. That would be a very short ballistic arc.

I've had more than enough practice with the Glock. I think I'm as good as I'm going to get with it unless I put on an adjustable rear sight.

No, the only thing that fits my hand are revolvers. And I hate revolvers. I have small hands and short fingers. For all semi-autos, I have to cant my hand around the grip to get the pad of my finger on the trigger. But the Glock grip is fatter and worse than some. Saving my $$$ for a single stack 1911.

Seven yards and under is contact distance -- and is where most pistol fights happen, statistically speaking, which is why some argue for a stronger emphasis on point shooting in training.

Many thanks for very helpful replies.