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Old October 10, 2012, 08:58 PM   #1
JohnKSa
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Where is my pistol sighted to shoot?

I see this question a lot and I've tried to provide answers on many occasions.

First of all, if your pistol has adjustable sights, there's a good chance you'll have to adjust the sights to get it to shoot where you want. It might be counterintuitive, but it's been my experience that an adjustable sight pistol is much less likely than a fixed sighted pistol to be sighted in when it comes out of the box.

If your handgun has fixed sights, then where it shoots depends on a few things, but, in general, it's been my experience that most fixed sighted pistols have the sights set more or less the same unless somebody screwed up at the factory.

They will usually be sighted to put the bullets directly on top of the front sight at 3 to 5 yards, a couple of inches above the front sight at 15 yards (suitable for a center hit on a 4" bullseye with a 6 O'Clock target hold), and about 4" above the front sight at 25 yards (suitable for a center hit on an 8" bullseye with a 6 O'Clock target hold).

Here's a plot that I made by collecting the data from targets shot at various distances today at the range. I shot the targets using an STI-GP6 and American Eagle 115gr 9mm ammunition.

The point of aim is the point on the target that is immediately above the front sight with the sights aligned properly.



I shot groups at 1, 3, 7, 15 and 25 yards and measured the elevation of each shot with respect to the point of aim. Then I averaged those elevations to come up with a single elevation figure for each range. The elevation figure at 0 yards is the distance from the top of the sights to the center of the bore since that's where the bullet is, with respect to the point of aim, the instant it exits the muzzle.

Note that since the barrel is below the sights, at the muzzle and at very close ranges, the bullet will actually impact BELOW the top of the front sight.

Because people want to be able to hit objects at farther distances, the bore has to be angled up very slightly with respect to the sights. If that weren't true, given the effects of gravity, the bullet would never rise to the line of the sights since it obviously starts out below the sights.

So the answer to the question that titles this thread is: It depends.

No matter how your pistol is sighted, it will shoot to significantly different elevations at different ranges.

However, one thing should be clear. It doesn't make sense for a manufacturer (or gun owner) to sight a pistol so that it hits significantly below point of aim at distances like 7 to 10 yards. It's become common for people to claim that certain guns are sighted this way, however not only has it not been my experience that such a thing is true, it doesn't make sense.

One can look at the plot and see that if the line angles downward, instead of upward, it will keep angling downward, and it will be closest to being on target at the muzzle--dropping farther down on the target as the targets get farther away.

If one were to sight a pistol with an initial sight height of 0.5" so that it hits 2-3 inches low at 7 yards (behind the front sight), we can calculate that it would have to hit the target about 4"-6" low at 15 yards and it would be 6"-9" low at 25 yards.

[Actually it will be lower than that because without the slight upward angle to "fight" gravity, the bullet's initial downward trajectory and gravity will work together to drive the point of impact even lower than these calculations show. The calculations assume a more or less linear trajectory which works well for a close range (inside 25 yards) approximation of a bullet trajectory with a typical slight upward angle at the bore. They will underestimate the effects of gravity if the bore is angled downward as it would have to be to achieve a point of impact at 7 yards that is significantly below the point of aim.]

When sighted like my GP6 (and most of my other fixed sight pistols) came from the factory, the bullet will only hit lower than the point of aim at very close distances. It must because the bore is below the sights, but, even then it won't hit very low as the shooting results in the plot show. The distance between the top of the sight and the bore centerline is very small--less than an inch, so it won't ever be lower than that until you get way out past typical pistol distances and the trajectory bends back downward due to the effects of gravity.
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Old October 10, 2012, 10:25 PM   #2
sigcurious
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Interesting, never really thought about this much, but with the data laid out it makes a lot of sense. Thanks for putting in the legwork on a common question.
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Old October 11, 2012, 09:58 AM   #3
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Good point well made.

The way I think of it is to imagine a line through the center of the bore and a line through the center of the aligned sights. POI equals POA only where those lines intersect. Since the sights are above the bore, the bullet rises to the line of sight to intersect it a certain point x feet out, and then continues to rise above the sight line until demon gravity takes over.
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Old October 11, 2012, 01:17 PM   #4
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Quote:
However, one thing should be clear. It doesn't make sense for a manufacturer (or gun owner) to sight a pistol so that it hits significantly below point of aim at distances like 7 to 10 yards. It's become common for people to claim that certain guns are sighted this way, however not only has it not been my experience that such a thing is true, it doesn't make sense.
I would add that there is enough difference in velocity to change your trajectory slightly. my 9mm (115gr @ 1150fps) that hit roughly 2" above the sights at 25 yards will hit just under the top of the sight blade at 7 yards while my 45 (230gr @ 800fps) with the same 25 yard zero will hit right above the top of the front sight blade. It's a very small difference but it's there.
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Old October 11, 2012, 02:07 PM   #5
Bob Wright
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I have never been able to do this, but thought about it several times:

Obtain a laser cartridge that fits the chamber of your gun. Load the "cartridge" with it turned on. Clamp your revolver in a sturdy tripod or other mount, and place a level across the sights so it rests on the top of the rear sight and top of the front sight blade, then level the bubble.(Assuming the sights are aligned with a bullseye at some range) It would be interesting to see where the laser is directed. Note line of sightand line of bore are not parallel.

This after the revolver (or pistol) is sighted in for a particular load.

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Last edited by Bob Wright; October 11, 2012 at 02:14 PM.
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Old October 11, 2012, 02:42 PM   #6
RickB
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I remember reading about a guy who watched a group of police rookies, or maybe it was still at a police academy, doing maintenance on their revolvers, including "tightening" the screws on the rear sights.
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Old October 11, 2012, 02:59 PM   #7
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POI is a factor of grip, recoil, and bullet velocity. A mechanical alignment of bore and sights is not necessarily a useable sight setting.
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Old October 11, 2012, 04:04 PM   #8
Clifford L. Hughes
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John:

Mobuck is correct. pistol bullets are still in the bore during recoil. A properly sighted pistol's sights will point lower than the impact of the bullet. This is due to the bullet's lag time in the bore. That is why heavy bullets strike highrt than light bullets.

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Last edited by Clifford L. Hughes; October 11, 2012 at 04:06 PM. Reason: spellling
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Old October 11, 2012, 04:31 PM   #9
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Great thread. Thanks, JohnKSa for the nice summary and chart.

There's always something more to learn.
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Old October 11, 2012, 06:04 PM   #10
Bob Wright
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Mobuck wrote:
Quote:
POI is a factor of grip, recoil, and bullet velocity. A mechanical alignment of bore and sights is not necessarily a useable sight setting.
Quote:
Note line of sight and line of bore are not parallel.

This after the revolver (or pistol) is sighted in for a particular load.
My point exactly.

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Old October 11, 2012, 07:51 PM   #11
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I saw john's chart, and assumed satellites everywhere are in danger. Good read, kinda funny charter, though!
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Old October 11, 2012, 09:10 PM   #12
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Quote:
POI is a factor of grip, recoil, and bullet velocity. A mechanical alignment of bore and sights is not necessarily a useable sight setting.

Shooting one handed versus two handed changes the point of impact also, because of the greater resistance to recoil when shooting two handed. The farther the distance, the greater the effect. Shooting 300 yards with the glock 19 requires a different sight picture one handed compared to two handed. It appears to shoot "flatter" one handed, since it requires less sight held up.
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Old October 11, 2012, 10:48 PM   #13
JohnKSa
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Quote:
I would add that there is enough difference in velocity to change your trajectory slightly. my 9mm (115gr @ 1150fps) that hit roughly 2" above the sights at 25 yards will hit just under the top of the sight blade at 7 yards while my 45 (230gr @ 800fps) with the same 25 yard zero will hit right above the top of the front sight blade. It's a very small difference but it's there.
Right, one could reduce the slope of the line and the bullet would stay below the top of the front sight for a longer distance.

However, even in that case, the point of impact won't be very much below the front sight because it's still traveling on an upward path over the distance out to 25 yards and it only started maybe a half inch below the sights to begin with.
Quote:
I saw john's chart, and assumed satellites everywhere are in danger.
Yeah, the scale is amplified to make the graph clearer--but it does give the impression of an inevitable upward trend, doesn't it? Of course, if I were a good enough shooter to make decent groups out past 25 yards, and took the time to collect data at the longer distances we would eventually see gravity take over and the trajectory would bend downward.
Quote:
POI is a factor of grip, recoil, and bullet velocity. A mechanical alignment of bore and sights is not necessarily a useable sight setting.
That is true, however it's usually not a major factor in locked breech autopistols because the recoil of the pistol while the bullet is still in the barrel consists primarily of slide/barrel movement and not much muzzle rise. There isn't much muzzle rise until the barrel impacts the frame and its momentum is transferred to the frame which causes muzzle rise. But before the barrel unlocks and hits the frame, the bullet is long gone. So it isn't affected much by recoil-induced muzzle rise.

(Of course, there's more momentum transferred--and more muzzle rise induced--when the slide is stopped at the end of its travel but that's much later in the cycle and not particularly relevant to this issue).

The graph shows that there isn't much muzzle rise in this particular pistol while the bullet is still in the bore--at least not the way I was holding it. Remember that the 0 yard figure is the actual distance between the top of the front sight and the centerline of the bore. Had muzzle rise been a big factor in the point of impact for this pistol, the trajectory numbers wouldn't have lined up well with the 0 yard figure. The 0 yard figure would appear to be low because the other numbers would have been bumped upward by recoil-induced muzzle rise.

Perhaps at very long ranges, the small effect would be magnified enough to show up.

I'll repeat this someday with a revolver so we can see the difference.
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Old October 12, 2012, 01:51 AM   #14
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Geezze- La-Weese!

So the big question is...drum roll please.....where is your zero on your gun you have packed-away to stop zombies with tonight?

Don't feel bad. No one else knows either.
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Old October 12, 2012, 02:04 AM   #15
James K
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Unless they have changed, S&W .38 Special caliber fixed sight revolvers are made to put the standard 158 grain bullet dead on point of aim at 25 yards, with the point of aim being exactly on top of the front sight, not above or below it.

GI .45 ACP pistols were also sighted at 25 yards with GI ammunition with the same sight picture.

Jim
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Old October 12, 2012, 02:28 AM   #16
warningshot
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Close. Of the 4 inch Smith and Wesson K and N frames and Colt Official Police & Lawman models that I came across, 99% shot high because the gun industry built them that way while expecting the instructors to only teach the recruits a 6 o'clock hold method. After that failed, LE went to a funny looking dude with his hand on his hip target that had a max point value area the size of a barn door.

As far as the military .45 acp 1911A1s went, just make them operational with all the parts, including a front sight, keep track of the guns and get them issued. A zero? On this POS? Bore me. Well, that's how I remember it.
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Old October 12, 2012, 02:41 AM   #17
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I came to the same conclusion a while back. I noticed that every pistol I own has a POI 3-5 inches high at 25 yards.
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Old October 12, 2012, 02:52 AM   #18
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Yep! That is it! You can find some real good deals on these fixed sighted revolvers because their previous owners couldn't hit much with them so the guns were not shot a lot.

I've discovered that if you use a light bullet at a high velocity you can get the POA POI closer within the 7 to 17 yard range. Say a 110 grain jacketed bullet at 930 feet per second using a fast powder like Bullseye or W231. It is all fun if you don't take yourself to seriously.
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Old October 12, 2012, 11:58 AM   #19
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Trajectory

All firearms are set up to shoot the projectiles(s) upward at some degree. Somewhere along the bullet's line of flight, the bullet reaches the top of the trajectory - as high as it will get - and begins to drop. Obviously this distance changes with the velocity and ballistic coefficient of the projectile. The faster and less prone to loose velocity, the further the bullet will travel in a given amount of time, and the 'flatter' the trajectory.

So, one desires a handgun (or rifle, shotgun, machinegun) to have sights aligned with the direct path of the bullet with no deviation in windage. The bullet strike for elevation will vary with distance.

Here's the trick: The elevation variance is negligible within certain distances. (In a military rifle, this is called 'battle sight zero'. In a pistol, it's just the normal sight setting and doesn't have a title.) For instance, a .45 ACP hardball round, fired from a Government Model pistol - if sighted in two and one half inches high at 50 yards, will strike about seven inches below line of sight at 100 yards. (According to the Chuck Hawk website information). For self defense purposes, one does not need to change sight picture to hit a torso sized target out to 100 yards.

A 9x19mm pistol is similar, but not exactly the same. Three inches high at 50 yards will strike just less than two inches low at 100 - for a 124 grain bullet at 1100 f/s.

Before anyone gets all worked up about shooting a handgun at 50 or 100 yards, the point is, a single sight setting will serve for any given loading.

More than that, switching loads will not change the point of impact so radically one's sight setting need be adjusted. This still in the context of self defense, and the target area being the size of the "8" ring of the NRA B27 target - about 12 x 18 inches.

For precision bullseye shooting, adjustments need be made to score X ring hits.

Just for the tally book, the bullet crosses the line of sight - according to the sights - twice; once on the upswing and then again on the downswing. (This is a very useful fact when sighting in a brand new rifle, or a new scope or sights on an old rifle.)

And - just for the tally book - the term 'point blank' refers to the distance a firearm and cartridge will strike a defined size target WITHOUT changing the sight setting. It does not mean "can't miss" range, contrary to semi-literate reporters or television characters.
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Old October 13, 2012, 01:15 AM   #20
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I shoot my .38 Airweight snub with GDHP 135g +P and about 20-24" low of CM at 50 yards, and get very close hit's to CM. That's up and down not side to side, that's all me.

But that might be the way I line up my sites. I let a guy shoot the same gun at 50 and told him to shoot low. He shot about the same to CM.
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