It's 6 'o Clock: Do You Know Where Your POI Is?

[Rebel Zero]

Hi, all;

Some questions for you. I just swapped my Springer XD .40 for an XD .45 compact. Thus far I absolutely love it. I shoot it much better than the .40 for some reason and it fits my hand perfectly.

Since I was never dead-on with the .40, I seldom moved the target out to 20 yards. On my first day with the .45 I put 9 of 13 rounds into a ten inch target at 20 yards. Unfortunately, the range I frequent is indoors, and 20 yards is the max. Considering how much more accurate I was right off with the .45, I'd like to try it at greater distances. I'm curious about some stuff, though.

Springfield states that at distances of 25 yards and beyond, the XD is set up with a "6 'o clock sight picture." Is this superior to POA at this range, or is it a matter of preference? What's the reason for this set up? How, exactly, do you you judge this? By this, I mean when you're looking down range and focusing on the front sight, how far below your projected POI do you aim? Six o clock is vague: anywhere directly below your projected POI and above the deck is six o clock.

Can a gunsmith set the XD's sights so that they're POA at any range, or should I just shut up and learn to shoot it as is? Does any of this make any sense? I feel like I'm not expressing myself very well, but, hey, I'm a newbie. What're ya gonna do?

I hope someone can shed some light on this for me. Thanks in advance.

-RZ

 

[BHPshooter]

Can a gunsmith set the XD's sights so that they're POA at any range

The basic answer to your question is no. The reason is that the sighting plane is a perfectly straight line, but the bullet's path is not -- it's actually an arc. If you ever want to know just how much those babies drop, get some tracers.

What that means is that the path of the bullet -- the arc -- intersects the sighting plane -- the straight line -- at two points. In between those points, the bullet will be high. Outside of those points, it will be low.

Since they say that the XD is set up to be POA=POI at close range, that means that the sighting plane must be pretty darn low in comparison to the projectile's path of travel. On the other end of the spectrum, if the gun were sighted to be zeroed at the apex of the arc, at any other range, you'd hit low.

The real secret to all of it is just to practice to the point where you know your POI inside and out. your first IDPA match is a real crash-course in that.

Wes

 

[gudel]

So any ideas how far the two distances indicated by the red arrows?

 

[Snowdog]

I was wondering what Thefumegator was talking about concerning the arc bit, as the bullet doesn't rise upwards after leaving a (stationary) barrel. However, I suppose the bullet could arc due to recoil (muzzle flip). In this case, I'd imagine different bullet weights would cause the amount to vary. This is evident when switching from 110gr to 158gr slugs in a lightweight .38special snubnose.

As far as shooting at different ranges, I can say... from experience, mind you... that you'll have to shoot your handgun enough to get a feel for it at different ranges. I doubt you'll find any lasting satisfaction monkeying with the sights unless they're really bugging you.

BTW, you'll likely shoot better outdoors. I found my "proficiency" increased dramatically when I started shooting outdoors. I suspect it's the lighting, but there's certainly some significant difference. Indoors I'm somewhat mediocre with handguns, whereas outdoors I'm downright decent.

 

[DMK]

I was wondering what Thefumegator was talking about concerning the arc bit, as the bullet doesn't rise upwards after leaving a (stationary) barrel.

The diagram is a little misleading. The gun would be angled up a bit.

Bullets don't rise. They actually fall at a constant rate. It's a race against gravity to see how far the bullet will go before hitting the ground. Assuming the sights are adjusted accordingly, a lighter, faster bullet will go further than a slower heavier bullet since it travels faster, therefore covers more ground before hitting the earth (Actually weight has nothing to do with it. Remember, light and heavy objects all fall at the same rate. Velocity and aerodynamics are what matter). We adjust the sights, angling the gun upward to take advantage of this and the result is a "ballistic curve" like the one shown.

 

[DMK]

Springfield states that at distances of 25 yards and beyond, the XD is set up with a "6 'o clock sight picture." Is this superior to POA at this range, or is it a matter of preference?

For target shooting with a round bullseye, a 6 'o clock hold can be preferable. It allows you to center the dot (the target) over the 'I' (the front sight). This can be easier to do than to try and hold the top of the front sight on the center of the target while obscuring half of it. It's difficult to judge the exact center of the target consistently, but much easier to define the exact bottom of the target.

What's the reason for this set up? How, exactly, do you you judge this?

The reason was explained above. Bullets do not travel in a straight line like a laser beam. They curve downward towards the earth. We fire them slightly upward so they will hit a point in space at a range that we determine (this is what 'zeroing' is). Springfield has obviously determined that for the pistol's intended use, a 'zero' at 15 or so yards would be beneficial. I'd agree. This puts the high point of the curve at around 25 yards. What goes up, must come down, so on it's way back down it will again cross zero at some range further out (Maybe 40 or 50 yards).

You can chart this fairly accurately with a ballistics program. There's a few free one's around. You'd need to know the velocity, the bullet's diameter and it's ballistic coefficient (how aerodynamic it is). These factors vary from round to round, even with the same bullet weights in the same caliber.

The best way to judge this with your gun and your ammo is to shoot it from a rest at different ranges. Make notes as to where your POI is. If you're 4" high at 25 yards, then you need to hold a little low at that range. This is one reason center of mass shots are taught for self defense. You have a little leeway. 4" off either way will still hit vitals.

Massad Ayoob once wrote an article about this very topic. He told the story of a barricaded rifleman that held officers at bay about 100 yards out. They were only armed with handguns. The marksman of the bunch tried to hold over but did not know his exact drop for that range. He actually over compensated and when the situation was resolved, they found his shots in a nice group right above the doorframe where the rifleman was standing.

(elevation and other atmosphere conditions affect ballistics too, although it will probably be almost negligible with a short range handgun)

 

[MCgunner]

The effects of bore axis/sight plane aren't as pronounced in handguns. Maybe google "point blank range" or "rifle exterior ballistics". In rifle shooting, this "arc" of the bullet is well known. It is caused by the fact that gravity affects the bullet as soon as it exits the bore. Add to that the fact that the bore axis is typically 1.5" below the sight plane in a rifle, and you have to consider these things when you're shooting out at long range. You'll have hold over for shots out at 400 yards or beyond even if you have a rifle that can shoot a 300 yard 3" point blank range (a really "flat" shooting rifle).

I never really pay attention to such things shooting handguns out to 25 yards. At 50, there'll be a little hold over and I have a sight wire embedded in my .38 snub to help me when I'm playing at the range at 100 yards. It's fun shooting at a 12" slip blind at that range, actual target is about 15 inches diameter and you can ring it 2 or 3 shots out of five if you concentrate, but you have to adjust your sight picture rather radically to account for drop at that range. The gold wire in the sight is an old Elmer Keith trick, gives you a reference for long range sight picture.

 

[Rebel Zero]

Cool. Thanks, guys. This helps. I'm gonna head to the range to day and get some more trigger time.

RZ

 

[BHPshooter]

The diagram is a little misleading. The gun would be angled up a bit.

Bullets don't rise. They actually fall at a constant rate.

That's right. It was just a quick and dirty MS Paint job.

So any ideas how far the two distances indicated by the red arrows?

That will be a case-by-case situation dependent on the individual gun and caliber. And two guns of the same make and caliber may be different in that regard also.

Wes

 

[DMK]

That's right. It was just a quick and dirty MS Paint job.

No need to be embarrassed. It's a good diagram.

 

[Majic]

What's the reason for this set up? How, exactly, do you you judge this? By this, I mean when you're looking down range and focusing on the front sight, how far below your projected POI do you aim? Six o clock is vague: anywhere directly below your projected POI and above the deck is six o clock.

The old simple explanation is to think of a lollipop. The candy (which represents the target) sits directly on top of the stick (which represents the front sight). There is no gap between them.

 

[sfmittels]

If I remember my ancient history, the "six o'clock hold" came out of Bullseye competition. As was pointed out in an earlier post, it is easier to define the black bullseye target if it appears to be perched on top of the front sight blade. Bullseye guns with adjustable target sights were (and perhaps still are - I stopped competing when my eyes began requiring bifocals) adjusted to actually hit a bit higher than POA. Since distances and target dimensions are standardized for Bullseye, you can sight your competition gun for a six o-clock hold and get SERIOUSLY precise with your aiming with iron sights.

Years ago, I had a Colt Gold Cup set up with a softball recoil spring (that's a lightweight spring designed to function properly with light-loaded .45 ACP wadcutters). It was sighted for a six o'clock hold. I shot some amazing scores with it. Of course, in the real world, the sight setup was difficult to use, because you had to estimate how much to hold your front sight UNDER the target if you were within normal distances of the target. But then you'd have to guestimate how much to hold OVER the target at extended ranges, given the rainbow trajectory of the .45 ACP, especially softball loads. And if you wanted to shoot full-power .45 ammo, you had to remember to get that softball recoil spring out of there or you'd batter your frame. All in all, it was a PITA if you wanted your 1911 to serve dual purposes.