What role does probablity play?

[Bighorner]

I'm not a long range hunter and am amazed at some people's capabilities when it comes to long range shooting.

I do have a legit question. Assuming a rifle shoots MOA and assuming a rifleman can not shoot with zero error, isn't there a theoretical limit to shots without banking on only a probability of a hit?

If my rifle shoots 1 more, at 700 yards the rifle is reliably hitting within a 14" diameter circle. If shooter introduced any error that circle expands. We aren't machine and we aren't shooting a under controlled environment. If a deer's vitals are approximately covered by that 14" diameter circle aren't you just playing a game of probability that you will make a good shot? If your rifle shoots 5" left and shooter error sends the bullet 7" right you are golden, but that is just canceling errors rather than a compoinding errors. Two errors to the left results in a miss or wound.

Is this sound logic or am I missing something? I am asking with all due respect.

 

[Felix40]

Your MOA calculation is off by a factor of 2 but yes at a certain point what you are saying is true.

 

[Bighorner]

Thank you, that would be a 7" diameter circle which tighten things up a lot. Good catch.

 

[long hunter]

I enjoy long range shooting 600 yards is my limit, willl try everything too close the gap and it must be a exceptional animal before taking that shot, beyond that the animal lives for another hunt. And yes I spend a shit load of time on the range shooting paper.

 

[cmahoney]

You should be able to get your rifle shooting better than a minute too, especially if you dump as much money into them as I do.


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[Bighorner]

I appreciate the in put, just trying to wrap my head around at what point it becomes an educated role of the dice. I get that everyone has their comfort range and how much risk is acceptable. I understand that both those factors will vary by person. I couldn't really find much addressing the probablity component.

 

[Megalodon]

I don’t really even understand your question. It becomes a case of “probability” if you group size at the distance you’re shooting is larger than the target. If your gun is only capable of 1 moa and you’re shooting a 5” target at 1000 yards, it’s just chance if you get a hit or not.

When you introduce the human factor everything becomes less predictable. You could have a .25 moa gun, a 10” target at 100 yards and pull the shot and miss. Read the wind wrong, distance wrong etc.

No shot is guaranteed, there’s always a probability of a miss.

 

[Reburn]

There is a ton of info on this site about hit probablilities and even a calculator on here somewhere.

Far and away wind dope is the biggest factor in LR misses (500 yards plus)

 

[Bubblehide]

It depends on the competency of the shooter and their equipment. The proper use of the right equipment and a sub MOA rifle in the right hands of someone that does not take shots in high wind conditions maximizes the likelihood of hitting their target where they want to hit it. That and consistent practice. Many also shoot from tripods, minimizing potential shooter errors.

However, long range is a relative term that means different distances to different people.

 

[Bighorner]

What I'm asking is how confident are you at you self imposed max range. When I started thinking about it was a matter of the probability. For example at my max range I am 90 percent confident or 99 or 75. I get that changes for everyone. I just personally don't know any real long range guys. Meaning everyone take a poke at the 500 yard going, but few people really understand what they are doing or are willing to get good dope.

 

[Bighorner]

So not the probablity of hitting the target, but taking that probabilty into whether to take the shot.

Probably varies too much to even ask.

 

[Bubblehide]

I simply do not take shots at animals I do not feel very confident with, with the exception of coyotes.

 

[nimrod_gn]

Everybody should read this: https://precisionrifleblog.com/2015/06/09/how-much-does-it-matter-overall-summary/

 

[Flyjunky]

Everybody should read this: https://precisionrifleblog.com/2015/06/09/how-much-does-it-matter-overall-summary/

Thank you so much for posting this. I was looking for this article a few months ago but I couldn't remember where I had found it!

 

[Bighorner]

Everybody should read this: https://precisionrifleblog.com/2015/06/09/how-much-does-it-matter-overall-summary/

That was really helpful. I appreciate it.

 

[MaraviaDave]

I recently created a Microsoft Excel based tool that calculates your probability of hitting a target. It allows study of the effects of rifle and environmental variables and uncertainties on hit percentage.
Read below, and check out the screenshot to see what it’s all about. I am sharing this with the community for free.


Note - you will need Microsoft Excel on a computer in order to run this tool. Versions of Excel for your phone will not work, as they don’t support Excel Macros.

MERC Download Link


Introduction to MERC - Maximum Effective Range Calculator
In a perfect world, the bullets would always leave your barrel in the direction you intended with identical velocities, and there would be no uncertainty in your wind or range estimation - you would hit your target's center with every shot. Unfortunately, we have to contend with variation and uncertainty in the real world.

This calculator lets the user specify information about their rifle and the shooting conditions, including the uncertainty in each input. The calculator applies an amount of random variation based on those specified uncertainties, and determines where the bullet would have hit. It then repeats this process for many hundreds of shots, and calculates a hit probability based on the number of hits and misses. It also plots the hit locations for the first 300 of these shots on a graph, to visually show the distribution of their impacts.


What can I use MERC for?
MERC can be used to study many shooting situations. Here are some examples to get you started:

• Comparison of one cartridge/rifle/bullet to another. For a given set of conditions, which has better hit%, etc.
• Identify the longest range you would be comfortable hunting at, given a specific set of conditions and uncertainties.
• Estimating what hit rates to expect for a yardage that's farther than you've shot before.
• Comprehend how errors in your scope zero affect hit probability.
• How much does "x" variable matter. For example, does a 0.5 MOA rifle help my hit% for my shooting scenario? How about StdDev in MV?
• How accurately do you need to estimate range and wind in order to have consistent hits?
• For a desired hit percentage, how much extra range does using a higher BC bullet provide?
• Understanding how wind angle uncertainty can cause groups that aren't centered around your point of aim.

Special thanks to Scott B. (entoptics on LRH), who convinced me that it would be worthwhile to release this tool to the shooting community. Together, we jazzed up the user interface, design/layout, instructions, and many other details. Hopefully you find it useful!

View attachment 213680

The M.E.R.C. tool is very valuable for calculating hit probabilities. You can make changes to the input variables (MOA, range and wind estimating accuracy, velocity SD’s and ES’s, etc) and see their affects on hit probability (percentage). I would imagine spending time with this tool will answer a lot of your questions.

However, hit probabilities is only one piece of the puzzle. Consideration needs to be given to terminal ballistics. Is your bullet going to do it’s job when it gets to the target. Does the bullet have enough velocity to comfortably meet the minimum velocity for adequate expansion? What type of bullet is it…..heavily constructed controlled expansion or something more frangible?

Also, a rifle may be capable of 1 MOA at 100 yards. But that doesn’t mean you’ll maintain that same level of accuracy at distance. Truing your ballistic software is critical. Use paper targets when truing, as opposed to steel, combined with Ballistic-X….. it’s important.

Learning to read wind and the effect on accuracy when shooting from different types of positions are other areas of focus that need to be worked on as well.

 

[Formidilosus]

I appreciate the in put, just trying to wrap my head around at what point it becomes an educated role of the dice. I get that everyone has their comfort range and how much risk is acceptable. I understand that both those factors will vary by person. I couldn't really find much addressing the probablity component.

It’s always an educated roll of the dice- there is no such thing as “100%” certainty. However, very, very few ever get to the point where they are thinking and acting based on real numbers or probabilities. The Applied Ballistics WEZ calculator is a fantastic tool, but it only works when real, unbiased numbers are input. And unfortunately even most people that do use it put in their wishes/best ever/hopes/etc, instead of something resembling data.
Take the comment that sub MOA is not that difficult/easy/etc. It’s not that difficult to randomly get a couple of rounds close together and claim “sub moa”, it’s another thing entirely to shoot enough shots into a single target, or enough single shots into single targets to state that a rifle is sub moa. You’re talking 20+ rounds with NO CALLED FLIERS. Every shot counts. Oh, and it needs to be done from the position that you’ll shoot from. I.E.- the WEZ is different from prone, than from sitting on a pack even with the exact same rifle and shooter. If people put in real data, with real numbers, they’d be shocked to see how low hit percentages are for them and their systems in field conditions.

We miss do to the largest sources of error. The largest sources of error in order tend to be-

1). Shooter incompetency
2). Accuracy due to positions other than prone
3). Incorrect zero
4). Optic failures
5). Incorrect data

And then, if all of those are addressed properly- Wind (#6). One can argue for different positioning of 1-5, and for each person they may be in a different order, however they’re all in there. 1-5 are baseline fundamentals and yet are very rarely all addressed. But let’s say someone gets through 1-5, wind is the number one source of error, and it’s not even close to the next one. After wind errors it would be inaccurate ranging (#7).
Of course everyone screams “LRF” yet I have watched repeatedly over the last month person after person range animals incorrectly due to not knowing where their laser is zeroed and under or overshooting in broken terrain by 10-20% on average.

Notice that precision- that is group size hasn’t been listed yet. No muzzle velocity or MV standard deviation or extreme spreads, nor any of the other mouse turds that most pole vault over. We miss do to the largest sources of error, and those are 1-7 by a huge margin.

 

[MaraviaDave]

It’s always an educated roll of the dice- there is no such thing as “100%” certainty. However, very, very few ever get to the point where they are thinking and acting based on real numbers or probabilities. The Applied Ballistics WEZ calculator is a fantastic tool, but it only works when real, unbiased numbers are input. And unfortunately even most people that do use it put in their wishes/best ever/hopes/etc, instead of something resembling data.
Take the comment that sub MOA is not that difficult/easy/etc. It’s not that difficult to randomly get a couple of rounds close together and claim “sub moa”, it’s another thing entirely to shoot enough shots into a single target, or enough single shots into single targets to state that a rifle is sub moa. You’re talking 20+ rounds with NO CALLED FLIERS. Every shot counts. Oh, and it needs to be done from the position that you’ll shoot from. I.E.- the WEZ is different from prone, than from sitting on a pack even with the exact same rifle and shooter. If people put in real data, with real numbers, they’d be shocked to see how low hit percentages are for them and their systems in field conditions.

We miss do to the largest sources of error. The largest sources of error in order tend to be-

1). Shooter incompetency
2). Accuracy due to positions other than prone
3). Incorrect zero
4). Optic failures
5). Incorrect data

And then, if all of those are addressed properly- Wind (#6). One can argue for different positioning of 1-5, and for each person they may be in a different order, however they’re all in there. 1-5 are baseline fundamentals and yet are very rarely all addressed. But let’s say someone gets through 1-5, wind is the number one source of error, and it’s not even close to the next one. After wind errors it would be inaccurate ranging (#7).
Of course everyone screams “LRF” yet I have watched repeatedly over the last month person after person range animals incorrectly due to not knowing where their laser is zeroed and under or overshooting in broken terrain by 10-20% on average.

Notice that precision- that is group size hasn’t been listed yet. No muzzle velocity or MV standard deviation or extreme spreads, nor any of the other mouse turds that most pole vault over. We miss do to the largest sources of error, and those are 1-7 by a huge margin.

I agree 100%

 

[Dos Perros]

Is MOA even formally defined? I get the minute of angle thing. But for a 1 MOA rifle, does that mean some percentage, maybe 2 standard deviations fall within that range? Obviously it can’t ever be 100%.

 

[Bighorner]

Let me ask it this way. How likely are you to hit a 14" target at 700 yards with a cold bore. In field conditions/winds variable at 5-10 mph? For an above average "long range hunter", is it 90% of the time?