Culmination point for 1911 .45 acp

MikiP

MikiP

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May sound overly technical, but I'm a new 1911 owner and shot my Para SSP Nite-Tac first time today to confirm sights and, well, to have some fun:D. I was good for line, but found POI was below POA on the first few serials (10-15 yard range). At first I thought I'd have to swap out my Trijicon front post for a shorter one, but then extended out to 20-25 yard, and found POI were mostly on POA. Thought more about this (I don't have a lot of pistol experience- infantryman for 15 years. so well versed on firing characteristics of of C7, C9, C6), and was wondering what the culmination point is for this round/caliber of pistol ie. when does the trajectory of the round hit its highest point, and what is the flight characteristics- how flat does she fly.

Maybe I'm overthinking this, but I just want to get to know my little bundle of joy:redface:
 
Most pistols are factory set with a POA/POI for 25 yards. All projectiles fly in a semi parabola that looks like the water out of a garden hose. Unless you the user mechanically compensates for the force of gravity, the projectile will always hit lower than the point of aim. Projectiles cannot and do not gain elevation, they only lose it. We compensate for this by adjusting sights and ultimately adjusting the barrel to an angle not perpendicular to the earths surface. A faster projectile will require less adjustment to hit the target at a specific range than a slower projectile. If you watch the shot put event the athlete must throw the shot at an extreme angle to achieve maximum distance. A baseball pitcher on the other hand does not need to release the ball much above 0 degrees/parallel to the ground to get the ball to the plate. The difference is velocity.

Without knowing for sure what distance the sights were setup for(assuming fixed sights) it is hard to determine if the issue you are experiencing is gear related or shooter related. I would say your results are typical and there is nothing wrong with the setup. The deviation at such minimal distances is almost negligible. Stretch it out to 50 or 100+ yards and the problem is more pronounced.

TDC

ETA: The high point in the trajectory is known as the max ordinate
 
Thanks for the reply. I understand the concept of object with mass over distance x velocity ie. it will drop proportional to the distance it goes. What I'm saying is that I was hitting lower closer into the target, and higher further away.

I'm dangerously close to leaving my knowledge zone and going off track, but we've proved this at work with the 5.56 at 25m (impact is lower than POA, could be height over bore?), 100m (hits 6" above POA), 200m (hits at POA) and 300m (hits 6" below POA) ranges firing with Iron sights. What stands out to me is that between the 25 and the 100m, the bullet has climbed above the line of sight, and the theory of a constant drop of projectile from leaving the barrel is killed, as what we've been taught in the theory is that there is still energy behind the projectile causing it to rise slightly.

This leads me to believe that there may be the same thing going on with what i described earlier, because as I moved further away from target, the POI climbed.

Thoughts?

Oh, and I'll add the "max ordinate" to my vernacular ;)
 
The bullet "rise" you mention with regards to the 5.56 in your previous post is not because of the projectile creating lift. The rise is mechanically introduced by the shooter by adjustment of the sights. Based on the numbers you gave, the zero you have set on the rifle is a 50/200 zero(give or take). With such a zero your impact at 25 is -1.6(this value is mostly the mechanical offset of the sight height above the bore line) is 0 at 50, 1.0 at 100, 0 at 200 and -6.4 at 300. To achieve a trajectory of 6" at 100 yards your zero is set to 400.

Regardless, the rise above the line of sight is a result of altering the angle of the barrel in relationship to the ground. This elevated muzzle/angle is determined by the sights and their subsequent settings.

The same is true for handguns. The difference is the ranges at which they are employed. At 25 yards and less, a pistol with a standard factory zero of POA/POI for 25 yards will result in near zero change in POI between muzzle and 25 yards. According to JBM ballistics page, a .45 cal 230gr projectile with a veloctiy of 880 fps will be within one inch of POA out to 40 yards. From zero to 25 yards(assuming a factory 25 yard zero) the deviation is less than .75 inches between POA/POI. Make sense??

TDC

ETA: With the same data as the .45 projectile above, your impact is only 16" low at 100 yards if we assume a factory zero of 25. With a zero range of say 100 yards, the max ordinate is 6.0" at 50 yards and continues at that level through to 55 yards before beginning its descent. With such an extreme zero, your POI at 25 yards is 4" high and at 15 it is 2.5" high and at 10 yards it is 1.5" high. So, even with an extreme zero of 100 yards for a handgun, the POA/POI deviation is not drastic at short ranges.
 
Yeah, I had a look at the JBM page- I entered the data from what you put above (I used Win. .45 230gr FMJ, I don't know what you entered), and maybe I'm reading it wrong, but the second column says there is a 4.8" drop (I think its treating it actually as a gain, as you can see that it gives negative digits out to the 100m) at the 40 yd, where as you're telling me it should be within 1" of POA. I'm confused?

I apologize for the table, it didn't hold onto the formatting

Calculated Table
RangeDrop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(m) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -1.5 *** 0.0 *** 880.0 0.788 395.4 0.000 0.0 ***
5 -0.2 -4.0 0.0 0.0 875.6 0.784 391.5 0.019 0.0 0.0
10 0.9 7.9 0.0 0.0 871.2 0.780 387.6 0.037 0.0 0.0
15 1.9 11.1 0.0 0.0 866.9 0.776 383.7 0.056 0.0 0.0
20 2.8 12.0 0.0 0.0 862.6 0.773 380.0 0.075 0.0 0.0
25 3.5 12.1 0.0 0.0 858.4 0.769 376.3 0.094 0.0 0.0
30 4.1 11.8 0.0 0.0 854.3 0.765 372.6 0.114 0.0 0.0
35 4.5 11.2 0.0 0.0 850.2 0.761 369.1 0.133 0.0 0.0
40 4.8 10.4 0.0 0.0 846.1 0.758 365.5 0.152 0.0 0.0
45 4.9 9.6 0.0 0.0 842.1 0.754 362.1 0.172 0.0 0.0
50 4.9 8.6 0.0 0.0 838.1 0.751 358.7 0.191 0.0 0.0
55 4.8 7.6 0.0 0.0 834.2 0.747 355.3 0.211 0.0 0.0
60 4.5 6.5 0.0 0.0 830.3 0.744 352.0 0.230 0.0 0.0
65 4.0 5.4 0.0 0.0 826.4 0.740 348.7 0.250 0.0 0.0
70 3.4 4.3 0.0 0.0 822.6 0.737 345.5 0.270 0.0 0.0
75 2.7 3.1 0.0 0.0 818.8 0.733 342.4 0.290 0.0 0.0
80 1.8 1.9 0.0 0.0 815.1 0.730 339.2 0.310 0.0 0.0
85 0.7 0.7 0.0 0.0 811.4 0.727 336.2 0.330 0.0 0.0
90 -0.5 -0.5 0.0 0.0 807.7 0.723 333.1 0.351 0.0 0.0
95 -1.9 -1.7 0.0 0.0 804.1 0.720 330.1 0.371 0.0 0.0
100 -3.4 -3.0 0.0 0.0 800.4 0.717 327.2 0.391 0.0 0.0
31/10/10 00:55, JBM/jbmtraj_simp-5.1.cgi

Yeah, this makes sense, and if I'm reading your ETA correctly (your saying at 25m POI is 4" higher than POA, right?) your numbers speak to my experience today. Only issue was I was consistently a least 4-6 in. lower shooting closer in (where I should have been slightly higher than POA), than further out having the same POA (POI was at POA at 25m, where it according to this table should have been 3.5" higher), and from what I'm reading from you also confirms the table.

Basically, if I'm employing my marksmanship principles correctly (pretty sure I am) I'm shooting low. So, what I'm wondering is if I need to put a shorter front sight on to raise my POA, or just know my gun and compensate, and aim a tad higher.
 
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If I'm reading your posted data correctly, the zero you chose with the JBM page is set at 90 yards or somewhere close to, where your impact is -0.5 inches below your line of sight. Negative values are always used to express trajectories BELOW your line of sight, and the opposite is true for trajectories ABOVE your line of sight. Use the JBM calculator SIMPLIFIED listed below their standard calculator. A lot of the fields on the standard calculator are not necessary.

With the above info, your conclusion and my experience. I would say you and your abilities are the cause of the POA/POI deviation. A high strike at 25 yards of 4" is not the sights, which based on Para's site, your gun came with fixed sights. Such a high impact is a direct result of an aggressively angled barrel at the moment of firing. This can be caused by healing, pressing with the heal of the firing hand just as the trigger is depressed causing the muzzle to rise or breaking the wrist up. Most likely, it can be attributed to poorly aligned sights. Sights or no sights, the pistol will shoot straight and to POA from zero to 25 yards. The flight time on a 230gr .45cal projetile traveling at 880 fps over 25 yards is 0.086 seconds. I just calculated the results for a 124gr 9mm round with a velocity of 1170(about average for 9mm) and the trajectories from zero to 25 with a 25 yard "factory" zero are near identical. Oh, the 9mm takes 0.066 seconds so it does get there a little faster. Calibre, bullet style, make, etc make no difference when handguns are concerned. Some may cycle better or have a different felt recoil impulse, but their down range "accuracy" is a function of the shooter, not the gun or ammo.

I would suggest having someone else try your pistol, in fact have several people try it. Try and eliminate the human as the problem before spending time and money on bolt on bits and pieces. Its cheaper, and its an excuse to shoot and brag up your new chunk ;)

TDC
 
True story on the brag up part! A lot of envious eyes at the range :D

Thanks for your time giving the info, and again, I don't want to get into the numbers game here, you obviously have a lot more knowledge about ballistic properties than I do, but I think you think I'm striking high at 25 yards
A high strike at 25 yards of 4" is not the sights
Click to expand...
Whereas I'm actually hitting at POA at 25 yards- I just want to be clear.

Such a high impact is a direct result of an aggressively angled barrel at the moment of firing. This can be caused by healing, pressing with the heal of the firing hand just as the trigger is depressed causing the muzzle to rise or breaking the wrist up. Most likely, it can be attributed to poorly aligned sights.
Click to expand...

I've read thoroughly through your response, and I'm not "heeling", or adding back pressure- I'm not hitting high, I'm hitting low.

Sights or no sights, the pistol will shoot straight and to POA from zero to 25 yards.
Click to expand...

The data tells me different. I actually line graphed it, and it shows a parabolic curvilinear trend from 0 to 100 m, in 5m increments. I wanted to post it, but can't get photobucket to accept the .jpg format for some reason.

I'm actually anticipating that I should be hitting high, because from what I read from the data, I should be hitting 4" (3.5" actually) high at 25 yards.

I will have someone else shoot the pistol to confirm that it either is or isn't shooter error, but from what I'm seeing in the applied trend to ballistic data, my sight set up has me hitting low.
 
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Alright, lets straighten this out. At what range are you hitting low, and at what range(s) are you hitting high?

On another note, when you have others shoot your gun and when you shoot it next. Do it from a rest. Table, sandbags, something. Remove as much human error potential as possible. Also, don't tell others what your issue is or what you're looking for, simply ask them to group with the pistol as best they can.

TDC

ETA: Here are a couple links to pics describing trajetory.

http://www.google.ca/imgres?imgurl=...=isch:1&um=1&itbs=1&ei=ybjNTKigCIS6sQOctdiIDw

For the one below, scroll down to the graph of the .38 spl. The trajectory from zero to 34 yards is for all intense purposes, flat. The max ordinate is approx. 0.3 inches above bore line. The -0.5 inches you see at the zero line is the result of mechanical offset, the difference between where the sights are and the barrel below. In fact, the velocity data for the .38 is in the same region as most .45 loadings so the graph is a fair representation of what your pistol should be doing with a "factory" 25 yard zero.
http://rugerforum.net/ruger-double-action/10206-sp101-2-1-4-barrel-correct-load.html
 
Yup.

I'm not hitting High at all.

I am hitting low below POA at 5, 10, 15, and start to hit POA at 20, 25

Thanks for the links.
 
As the bullet is still in the upward part of its trajectory (being factory zeroed at 25) it makes sense you're hitting low at closer distances.
 
MikiP said:
How low should I be hitting?
Click to expand...

It depends on the range from target and the mechanical offset of your sights. Most pistol sights sit nice and low, close to the bore line. Your impacts should be slightly low, but not enough to notice nor matter. The closer the target, the lower the impact should be. To the point where at zero yards, your bullets should strike exactly the same distance below your intended point of aim as the barrel is below your sights. Example: your sights are .75 inches above the centre of the bore, your rounds should strike .75 inches below your POA at 1 yard or less. The further you get from the muzzle and closer you get to your zero range(assuming the factory 25 yard zero) the less the deviation should be until you reach the range where max ordinate occurs. If you use the second link from my previous post that distance will be around 17 yards, where your bullet will be just over .25 inches above your line of sight. Not enough to notice or care about.


TDC
 
Your impacts should be slightly low, but not enough to notice nor matter
Click to expand...

And this is where I'm concerned, because I shot a few serials at the 10-15m range, and was between 4"-6" low from POA.
 
If you're hitting POA at 25 yards but at the same time you're hitting 4 to 6 inches low at 10'ish yards then it's not your sights. When the guys are saying that it's normal to hit low close in they are talking about at most less than an inch. It's far more likely your hand control that is varying in style and placement as you gain trigger time with your gun.

Why I suggest that your grip and reaction to the recoil is altering as you shoot more is that you say you are hitting at POA out at 25 yards. Yet when shooting at 10 to 15 you're 4 to 6 inches low. Without altering the sights there is only ONE cause for such a big variation and that is that you've developed a flinch or other unwanted reaction between the time you shot at 25 and the time you shot at 10-15 yards. The gun itself cannot produce such a wide variation on its own unless the sights are altered.
 
It's far more likely your hand control that is varying in style and placement as you gain trigger time with your gun.
Click to expand...
Cool. Thanks for the help. This echoes I think what TDC was trying to tell me, though it didn't feel at all like I was flinching. I'll shoot it again, with support (maybe I'll get my wife to give me a hug and cheer me on:D) as TDC recommended to confirm that it is me.

Thanks all.
 
A superb way to check for flinch or other hand control issues is to have someone load your mags up for you and slip a snap cap round or two into the stack. Then have the same folks watch as you shoot. If you get to the "malfunction" and the tip of the barrel doesn't waver at all while the hammer goes "click" then you're in control and your groups will be spot on and tight. HOwever if we're right what the observer will see is a pull down or a "shudder" in the tip of the barrel. Given that you're current issue seems to be a pull down "flinch" I suspect the barrel will depress. However I've also seen others where the whole hand tries to help out the trigger finger and the entire gun sort of shudders from their variation in grip tension as the whole hand tighten in unison with the trigger finger. Such a thing produces more of a shotgun like spray pattern over the course of a box of bullets. It's just something else to watch out for.

Hey, if it was easy we'd all be superb crack marksmen, eh? Even now after many thousands of rounds of various calibers sent downrange I find myself backsliding and the old companion Flinch jostling my shoulder. Most recently he came by for a visit while I was shooting a bit of .44Magnum. The only up side to it is that I've gotten and corrected my flinch enough times that I recognize when I'm about to flinch or when I do flinch.

When it's not just a one shot passing sort of deal and it goes away right away I find that it's time to pull out the trusty .22 and work through some drills concentrating on a full stroke "to the stop" trigger pull. Starting out with the intention of pulling the trigger smoothly all the way to the stop and not thinking about the blast and recoil is a great way to "think through" the blast and correct a flinch. Doing it with a lighter recoil round I found was better than just dry firing because it's too easy to dry fire perfectly and then to still react to the blast and recoil. At least with a .22 there is still some blast and recoil but it's not enough to have to do more than acknowledge it in passing. And by getting some practice at feeling it but ignoring it you develop the same lack of reaction to the big bore center fire recoil and VOILA! the flinch is gone.

For me the .22 was such a successful training aid, as well as being fun to shoot in its own right, that when asked which gun a new handgunner should buy I always say that if a .22 pistol isn't your first gun it should darn well be your second gun.

Anyhow, hopefully all this rambling helps out. And just to give you a little more here's my two most favourite freebie resources on holding a semi auto correctly. Perhaps some of this will help you out.

An excellent description of the two handed thumbs forward semi auto pistol grip. This write up ties in well with the next link.
http://www.handgunsmag.com/tactics_training/combatg_100306/

Todd Jarret in a trailer for a video on pistol gripping and shooting. Lots of good hints.
http://www.youtube.com/watch?v=ysa50-plo48

And the ever popular self help bullseye target for correcting bad groupings.
http://www.is-lan.com/challenge/images/Pistol-Correction.pdf
 
MikiP said:
Cool. Thanks for the help. This echoes I think what TDC was trying to tell me, though it didn't feel at all like I was flinching. I'll shoot it again, with support (maybe I'll get my wife to give me a hug and cheer me on:D) as TDC recommended to confirm that it is me.

Thanks all.
Click to expand...

BCRider has it right. The "mystery load" of your mags and/or pistol by a buddy is a great way to diagnose the flinch. The odd part about a flinch is that its almost undetectable by the shooter. For starters, you know when the gun is about to go off and you usually know if its loaded or not. Your body reacts just as your fire so the movement is masked by recoil. This is why I suggested shooting from a rest or sandbags, it prevents that stupid hand movement called flinching. Don't sweat it, everyone flinches, its a natural reaction. Through repetition and focus you can greatly reduce, almost eliminate your flinch. The faster you shoot, the greater the potential for the flinch to return, although a lot of the flinch associated with rapid shooting is more your conscious effort to return your sights to the target. Shooting skills are perishable and if you don't practice consistently, your flinch will return.

TDC
 
Thanks for all your help guys. I feel like a young Padowan (sp?) learning from his Jedi masters.

Watched Episode 1 Phantom Menace on Spike tonight.

Twice.
 
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