Accuracy Calculations - Points Lost to Inaccuracy

by bdas 1/14/2017, 10:55 pm

First topic message reminder :

How many times have you had someone suggest that you should spend your money to buy a better gun, part, or reloading component, or use a top-notch gunsmith, because it will increase the accuracy of your equipment? Or the reverse, where someone suggests spending your money on practice ammo or training aids, because that will improve your scores more than spending money to accurize your gun? I think it's pretty clear to everyone that, in competition, more accurate equipment leads to better scores. But how much better? I mean, would you pay $1000 to increase your score by 8 points in a bullseye 2700 match? How about $1000 to increase your score by 250 points? Those thoughts are nice, but most people talk about accuracy improvement in inches, not points. How many points will a 1" increase in accuracy get you? You need to know that before you can determine whether an expenditure on a 1" increase in accuracy is worth it. But I've never talked to anyone, or seen any post on any forum that really answers that question. If you think about it for a few minutes, you'll realize that's because it is not an easy question to answer. It depends on which target you are using (because they have different-sized rings), and where on the target you are aiming (because the rings on a given target are different widths), and it even depends on what caliber of bullet you are using. That's a lot of variability. So, being a computer programmer, I wrote a program that performs the necessary calculations.

The results are too large to post here, so I put them on my website: https://sites.google.com/site/davesguninfo/shooting---bullseye/accuracy-calculations
The results show points lost (or gained) by various levels of inaccuracy for each target with each caliber described in the NRA rulebook. The results also show points lost over 10 shots on each target, and even 90-shot sets (3 slow, 3 timed, 3 rapid, at various distances), again for each caliber. Which ends up being rather a lot of data. That page also contains information about how to make use the results, and how the program works.

Writing the program was partially inspired by this thread .45 bullseye pistol 1.5 guarantee, particularly one of the posts by mspingeld (and subsequent discussion) about the difference in scores between a 3" gun and a 1.5" gun for a shot at the edge of the 10 ring on a 50yd target (B-6) with a 45. I believe I have an actual answer to the question... the 1.5" gun is about half a point better than the 3" gun for that particular shot (which is a pretty significant difference, if you think about that kind of improvement over the course of an entire match)..

In addition to answering such hypothetical questions, the results are useful in evaluating many issues in bullseye shooting, such as whether it's worth it to buy and use new brass (see my post in this thread: Testing ammo groupings in a stock Range Officer at 25 yards), and many others.

Let me know if you have any questions about the program, the results, or how to make use of the results.

Dave

by bdas 1/24/2017, 9:03 am

Chris Miceli wrote:It's worth it when you clean your first target and you want to be in the sport to win.

I shoot to win, my goals are to spank me some shooters on the line and as I progress I am chasing down classes and working my way through them.

Nothing wrong if you want to shot for fun or to socialize, I'm not happy with the match unless I am #1

And that's another reason why I posted the results on-line, at various distances / calibers / accuracy levels for everyone to see and use... because everybody's situation (equipment, abilities/limits, skills, goals, budget, time, etc.) is different.

Putting your spanking fantasies aside for the moment ('cause I'm not sure I want to know how much you'd spend on those)...

It might be worth it to you to spend an extra $2000 to gain 8 points per match. Nothing wrong with that if it fits your situation.

by **Wobbley** 1/24/2017, 7:07 pm

The issue with a backer target to get the aggregate group is that the gun setup is rarely the same. If you do a center of impact comparison of the large group vs the shots in all the small groups they are seldom in the same place. Sometimes they're way off.

Best thing to do is to shoot 2 15 shot groups measure the radius from the center of the group and calculate the mean and the standard deviation. Two standard deviations will contain 95 % of all your shots. Once you have that number, you can then determine what the gun is capable of shooting. For even a 45 it should be an x ring or perhaps slightly larger at 50 yards. So your gun should give you a 499-47x at 50 yards and if you're not on the podium at Perry it is your fault not the gun.

mikemyers wrote:
Wobbley wrote:........I prefer a number of groups fired at least three and five is better.
I often use one backing board at the range, and put one target after another in the same place. Sometimes I felt good about the results - until I looked at the backing board from the rear.

Sorry for the interruptions - I'll go back to reading and learning.

by mikemyers 1/25/2017, 2:44 am

Wobbley wrote:The issue with a backer target to get the aggregate group is that the gun setup is rarely the same. If you do a center of impact comparison of the large group vs the shots in all the small groups they are seldom in the same place. Sometimes they're way off.

OK, not that I disagree with what you wrote, but what is the purpose in learning how to shoot "tight groups" if you don't know where that group is going to be centered on the target?

(What you wrote makes me feel better about my individual targets than the backing board, but that really means there is something else I need to correct.....)

by **Wobbley** 1/25/2017, 9:29 am

When testing ammo you're usually resting on bags (usually two handed) or in a ransom rest. The setups aren't the same and seldom is the impact the same as when shooting standing one handed.

by Chris Miceli 1/25/2017, 9:34 am

mikemyers wrote:
Wobbley wrote:The issue with a backer target to get the aggregate group is that the gun setup is rarely the same. If you do a center of impact comparison of the large group vs the shots in all the small groups they are seldom in the same place. Sometimes they're way off.

OK, not that I disagree with what you wrote, but what is the purpose in learning how to shoot "tight groups" if you don't know where that group is going to be centered on the target?

(What you wrote makes me feel better about my individual targets than the backing board, but that really means there is something else I need to correct.....)

that's is why you have sight adjustments?

by CR10X 1/25/2017, 10:37 am

In general, it works like this.

The nut behind the gun makes the groups (or maybe patterns).

The screws on the sights move the group (or pattern) on the target.

The two should not be confused.

CR

by mikemyers 1/25/2017, 11:07 am

CR10X wrote:......The nut behind the gun makes the groups (or maybe patterns)......

I assume we are talking about the "nut behind the gun" who may not pick the gun up exactly the same way each time, or position it in the hand exactly the same.

I learned long ago that if I shot several rounds, stopped for a bit, and then shot more, my existing group remained more or less the same. But, if I put the gun down on the table, and let go, and then picked it up again, there was a change. This has nothing to do with my sights, and everything to do with me.

(The best trick I learned, was to pick up the gun with my support hand, and feed it into the shooting hand. That alone made a difference.)

Maybe it's mostly "practice", or maybe it's something I'm not even aware of yet. I think it is relevant to this discussion, as someone buying a better gun, better also know how to hold it precisely every time they pick it up.

Or, to exaggerate, if someone was so good that they could put five shots through the same hole, consistently, what use is that if each group of five holes was in a different location on the target? :-)

by CR10X 1/25/2017, 11:39 am

If the person shooting the gun can put 5 shots touching with the the gun. Chances are that the center of that group will be the same, the next day, the next week, the next year; assuming the shooter does not change much.

(Changes in the group location are generally what the what the nut behind the gun needs to work on. Consistent grip, trigger process, hold, timing, focus, etc. But remember, every different load, every different type of ammunition, even changes in lighting, etc can have some effect on group location.)

I've got guns that were put at the end of the season, then shot again next spring. If I shot the same ammo and did what I was supposed to, the first shot was still an X.

And I prefer the term "training" versus "practice".

CR

by LenV 1/25/2017, 11:49 am

mikemyers wrote:
CR10X wrote:......The nut behind the gun makes the groups (or maybe patterns)......

I assume we are talking about the "nut behind the gun" who may not pick the gun up exactly the same way each time, or position it in the hand exactly the same.

I learned long ago that if I shot several rounds, stopped for a bit, and then shot more, my existing group remained more or less the same. But, if I put the gun down on the table, and let go, and then picked it up again, there was a change. This has nothing to do with my sights, and everything to do with me.

(The best trick I learned, was to pick up the gun with my support hand, and feed it into the shooting hand. That alone made a difference.)

Maybe it's mostly "practice", or maybe it's something I'm not even aware of yet. I think it is relevant to this discussion, as someone buying a better gun, better also know how to hold it precisely every time they pick it up.

Or, to exaggerate, if someone was so good that they could put five shots through the same hole, consistently, what use is that if each group of five holes was in a different location on the target? :-)

Sorta like this target. Two distinct groups (except for the "oops") All I did was change magazines and got the different groups. But score didn't change.

Accuracy Calculations - Points Lost to Inaccuracy - Page 2 Dscf0718

Accuracy Calculations - Points Lost to Inaccuracy - Page 2 Dscf0718

by daflorc 1/26/2017, 1:24 pm

sharkdoctor,

I absolutely agree with your assertion that it's a shortcoming of the program that it assumes a completely random distribution of the point-of-impact within the circle of inaccuracy. I seriously considered altering the weighting calculation to account for exactly what you're thinking... that many contributors to inaccuracy (such as the shooter's wobble area) will, statistically, be more likely to put shots in the middle of the circle, rather than at the fringes. However, it turns out that in almost all cases, such a change to the weighting calculation doesn't make a big difference in the calculated score. Why? Primarily because (a) the ring or rings nearest the point-of-aim already dominate the weighted score, and (b) such a change reduces the effect of both extreme point gains and extreme point losses, which end up balancing each other. Making the rings near the POA dominate the weighted score a bit more, simply doesn't change the weighted score very much.

Keep in mind that, although the results are carefully calculated without any rounding ('cause I'm a scientist type), and shown to 2 decimal places in the results tables, the real value is much more generalized than that. The value of the program is to tell you that (for example) a 1" increase in accuracy might yield, say, an 11-13 point improvement over the course of the 90 shots with that gun in a match. If the "true" improvement (if more variables were accounted for in the program) is really 9 points or really 15 points is not super-critical in my mind. The value of the program is knowing that it's not a 2 point improvement, and it's not an 80 point improvement. Getting an order-of-magnitude understanding of the level of improvement is (in my mind) helpful.

As I mentioned in my response to Jon, I think the results absolutely support the assertion that, unless taken to extremes, improvements in shooter skill will improve scores much more than more accurate equipment will (which is a valuable conclusion in and of itself).

But sometimes that improvement in skill is easier to say than do. The practice / training effort for a marksman to improve from a 73 average to a 76 average is usually not that great. In that situation, it's pretty easy to advise practice / training versus spending $1500 on better equipment to get such a 3-point improvement. But, I think we can all agree that the practice / training effort to improve from a 93 average to a 96 average is very significant. If (and I'm not saying that it could, but IF) spending $1500 on better equipment could buy you THAT 3-point improvement, I think quite a few experts would gladly spend the money. So, it's my opinion that it very much depends on your situation.

Thank you for looking at what I did, and giving well-considered feedback. I'm open to criticism and certainly agree with some of yours.

Dave

I think your program, and the conclusions you've made, especially as explained in this quoted segment, are brilliant. Bravo! If you could somehow figure out how many points on average can be reasonably expected to be picked up over 90 rounds for those shooting in each classification by using a 1.5" gun vs a 3" gun, that would take your data into a more easily understood realm that we all could benefit from. For instance, 9-10 points for an Expert, 5-6 points for a Master, 3-4 points for a high master, etc.

by Chris Miceli 1/26/2017, 2:23 pm

Put your gun in the hands of a high master if he shoots near his average it should take you to his level

by sharkdoctor 1/26/2017, 3:52 pm

Chris Miceli wrote:Put your gun in the hands of a high master if he shoots near his average it should take you to his level

The whole point of Dave's calculations and presentation was to mathematically predict the effect of a smaller grouping pistol.

If one is interested in investigating the potential of an increase in precision (smaller groups) of their pistol and effect on score, here is a simple seat of the pants experiment you might try.

Shoot thirty rounds at 50 yds (or 25) with your 45 for a composite group, and score. Measure the extreme spread. If you have a 3" gun, subtract that from the extreme spread. The remainder is a measure your ability to hold and break a shot. Now, reexamine the target, and score it by moving each shot in by 3/4". While an overestimate of the benefit (1/2 of the points added is closer) it would approximate having a 1.5" gun. How do they compare? I'll predict dispersion due to hold and break is several fold greater than group size.

by bdas 1/30/2017, 9:36 pm

daflorc wrote:
I think your program, and the conclusions you've made, especially as explained in this quoted segment, are brilliant. Bravo! If you could somehow figure out how many points on average can be reasonably expected to be picked up over 90 rounds for those shooting in each classification by using a 1.5" gun vs a 3" gun, that would take your data into a more easily understood realm that we all could benefit from. For instance, 9-10 points for an Expert, 5-6 points for a Master, 3-4 points for a high master, etc.

First, thank you for the kind words. Second, regarding your suggestion of showing points lost/gained over 90 shots for people in various classifications using equipment with different levels of accuracy... is at least what I was TRYING to do with the 90-shot tables.

Probably the one most people on this forum discuss the most is at 50yd slow fire and 25yd timed & rapid with a 45 caliber pistol. That 90-shot table can be found here: https://sites.google.com/site/davesguninfo/shooting---bullseye/results_45s#match900_150
Each row represents a sampling of shots (shown in the leftmost column), and each column represents a level of accuracy. You look across a row that approximates your scored shots (on a target that you consider typical for yourself), and then you compare the resulting score of various columns in that row. The difference represents the expected difference in score for that 90 shots. Let me know if that is not clear, or could be improved.

But, if you're interested in a different bullseye caliber (22LR, 32ACP, 32 S&W long, 38 Special, 9mm, 40 S&W, 44 Special) or a different set of bullseye targets (25yd, 20yd, 50ft), the other results tables have you covered.

What I'd REALLY like is a website that allows me to set up a web app with the program behind it, where you can enter/select some of the variables with values that are relevant to you (such as the POAs from one of your actual targets, or whatever accuracy levels you care about, or targets, etc.) and it would calculate results on the fly for you. But that's a different issue.

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Accuracy Calculations - Points Lost to Inaccuracy

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