How Many Rounds to Carry

[Kleanbore]

No one--NO ONE--can predict with any certainty how many rounds might required to stop a violent criminal attack requiring the use of deadly force.

The subject has been discussed ad nauseam in numerous threads here over the last several years.

Much of the discussion has been based on unsupportable assumptions and faulty logic.

It is by no means inconceivable that the mere presence of a firearm may obviate the need for the actual use of deadly force. But no one would advise carrying an empty gun.

The number of rounds needed will become an issue only when the shooting starts. And that number is really not possible to predict.

Member JohnKSa recently posted some analyses on The Firing Line that can greatly help with providing some relevant understanding. His post is copied below.

https://thefiringline.com/forums/showthread.php?t=589332

But first, some level-setting.

• It is important to understand that averages mean nothing. Your use of force incident could occur at a longer or shorter range, and require fewer or more rounds, than any mean, mode, or median values than one may be able to glean from reported data.
• Since we are speaking only of how many rounds might be needed after the shooting starts, the likelihood that a gun may be needed in particular circumstance or location is not pertinent to the issue at hand.
• One would not have to be attacked by a "gang" to need to defend against more than one person--perhaps two or three.
• Defensive shooting differs greatly from practicing at the square range; targets moving fast from unexpected directions, the element of surprise, panic and stress, the need to draw and shoot rapidly, and other factors will surely make hitting the assailants much more difficult than what we see in target practice.
• Another unknown is the number of actual hits that might be needed to stop an assailant. There are too many variables to count, but one thing to keep in mind is that to effect a physical stop, bullets must his small, key, moving parts of the body--internal parts that are not visible to the defender. That becomes very much a matter of chance. When we talk about "shot placement" in this context, we are not talking about bullseye shooting.

One other thing--the subject of extra magazines and speed-loaders invariably comes up. I suggest that everyone participate in or observe a "Tueller" scenario, consider how difficult it is to succeed in one, and ponder just how one would make use of a reload in such a circumstance.

Thanks much to John for taking the time and putting in the effort to prepare the following for us.

I believe it worthy of careful study.
______________

From JohnKSa:

Capacity, Hit Rate and Success. A Look at the Probabilities.
I've put together a number of plots that some may find useful.

How to use the plots.

The plots come in pairs. Each pair assumes at least a particular number of hits required for "success". The number of hits required for "success" ranges from 1 to 6 so there are a total of 12 plots. Although the plots are labeled with: "Success = X Hits" it would probably be more accurate for the labels to say: "Success = At Least X Hits" or maybe: "Success = X Or More Hits"

If the plot has "Hit Rate Probability" along the bottom of the graph, then each colored line on the plot represents the range of probabilities of success for a given capacity from 4 shots to 15 shots. Note that the lines on the plots are in the same vertical order as the legend on the right of the plot. You can pick a line representing a particular capacity and trace it across the graph to see how different hit rate probabilities will affect the chances of success for that capacity.

If the plot has "Number of Shots" along the bottom of the graph, then each colored line on the plot represents a range of probabilities of success for a given hit rate ranging from 10% to 90%. Note that the lines on the plots are in the same vertical order as the legend on the right of the plot. You can pick a line representing a hit rate probability and trace it across the graph to see how different capacities will affect the chances of success for that hit rate.

You can also use the plots to find the chance of success for a specific set of assumptions.

Example:

To find the probability of hitting a target at least 2 times (2 or more times) out of 8 shots with a hit rate of 50%, first find the pair of plots which are labeled "Success = 2 Hits". If you pick the plot that has "Number of Shots" across the bottom, then find where the axis is labeled 8 and trace the gridline up to where it crosses the "50% Hit Rate" line. If you pick the plot that has "Hit Rate Probability" along the bottom of the graph, then find where the bottom axis is labeled 50% and trace the gridline upward to where it crosses the "8 Shots" line. In either case, read the probability of success off the axis on the left.

The range of hits required to achieve success (1-6) is designed to cover what a person might reasonably be expected to require to solve a self-defense encounter. Might it take more or less? Of course. But going less than one doesn't make sense and making the graphs takes time so I stopped at six. If someone is really concerned about the probability for a scenario requiring more than six hits, PM me and I'll run a special case for you.

Be reasonable when you choose your hit rates if you expect to get reasonable results. There may be some of us who could really be expected to hit 80 or 90% of our shots during a gunfight, but the outcomes of real world scenarios suggest that the number is probably considerably lower. I recall reading the analysis of one study that examined a large number of police shootings which indicated that the average hit rate in a gunfight was about 3 hits for every 10 shots fired.

The graphs do not provide "high fidelity gunfight simulation numbers". They provide probabilities based on very simple assumptions. No more, no less. It's best to think of them as sort of "best case scenario" outcomes. The probabilities in the real world won't be better than the graphs show for a given hit rate, capacity and required number of hits, but they could easily be worse.

Here are a few ways how that could be true.

1. You get shot before you can finish firing all your rounds.
2. You fixate on one attacker and end up "wasting rounds" on him even after he's been neutralized with the required number of hits.
3. Your gun jams before you can finish firing all your rounds.
4. You never get a chance to draw and fire.

The probabilities are about finding a proper balance.

Moving up in capacity obviously improves your odds of making the required number of hits before running dry, but you can't get carried away in that direction because it's not terribly likely that a person will be able to take advantage of a huge round count in the few seconds a gunfight typically lasts.

Improving the hit rate probability (sharpening shooting skills) clearly helps a lot, but even so, if you need to make more than just a couple of hits, you still need some capacity available to take advantage of that skill. And, practically speaking, there's a limit to how much we can improve our shooting ability.

I've posted on this topic before but this is the first time I've provided such a full range of plots.

Here's one discussion of this general topic. In that thread, I only ran one pair of graphs focused on requiring at least 4 hits as the definition of success. But there's a lot of worthwhile (as well as some not so worthwhile) discussion about what the numbers do and don't mean.
https://thefiringline.com/forums/sho...d.php?t=494257

The graphs can also be useful to counter the argument that no honest person needs more than a small number of rounds for effective self-defense.

Here's another thread where some of the concepts relating to the graphs and their probabilities were discussed.
https://thefiringline.com/forums/sho...d.php?t=589112

And now, without further ado, here are the graphs.

The following two plots show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least one hit (one or more hits). Note that with the higher hit rates and capacities, the probabilities compress to the top of the graph, meaning that success is very likely.

Attached Images

S=1_Cap_x=HR.jpg (231.1 KB, 131 views)

S=1_HR_x=Cap.jpg (228.5 KB, 126 views)
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The following two graphs show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least two hits before running out of ammunition.

Attached Images

S=2_Cap_x=HR.jpg (204.5 KB, 115 views)

S=2_HR_x=Cap.jpg (193.0 KB, 114 views)
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The following two graphs show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least three hits before running dry.

Attached Images

S=3_Cap_x=HR.jpg (221.5 KB, 115 views)

S=3_HR_x=Cap.jpg (208.6 KB, 115 views)
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The following two graphs show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least four hits before running dry. This might be used to represent a scenario with two determined attackers, each requiring a minimum of 2 hits to neutralize them.

Attached Images

S=4_Cap_x=HR.jpg (227.4 KB, 115 views)

S=4_HR_x=Cap.jpg (213.8 KB, 117 views)
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[boom boom]

I have double stacks in most of my SD guns and always carry an extra mag. The few times I carry my model 60 SW, I carry two speedloaders as well. According to Col. Cooper, I must be planning on missing a lot.

 

[Kleanbore]

Continuation:

The following two graphs show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least five hits. Note that the probabilities start at zero for the 4 shot capacity. That's because it's impossible to score at least 5 hits with only 4 shots.

Attached Images

S=5_Cap_x=HR.jpg (222.7 KB, 113 views)

S=5_HR_x=Cap.jpg (213.0 KB, 113 views)

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The following two graphs show how capacity and hit rate probability affect the chance of success if success is defined as scoring at least six hits. Note that the probabilities are zero for the 4 & 5 shot capacities. Scoring at least 6 hits with only 4 or 5 shots just isn't going to happen.

Attached Images

S=6_Cap_x=HR.jpg (213.6 KB, 113 views)

S=6_HR_x=Cap.jpg (209.6 KB, 115 views)

 

[Creaky_Old_Cop]

Graphs and statistics...I have yet to be in a violent encounter with either.

I carry two reloads for my primary. No, not because I expect to be in a protracted gun battle with the forces of evil now that I am retired, though I allow for the possibility, but because as on any quality bottom feeder the magazine is the weak link in the mechanical chain. I want a mechanical redundancy, and a pair of spares have the advantage of balancing the load of the pistol on the opposite side of my belt and saving my back and knees from an unbalanced load. Yes, this is a real thing. I never cared how much stuff (am I allowed to say "stuff" without getting scolded by 19 mods for a language violation?) I had to carry on my duty belt as long as it was distributed well.

So, statistics. Cool. Never had a statistic pull a knife or a gun on me. Had a few miscreants over the years do it though. Hit ratios and hit percentages. Meh...don't care how often YOU miss as long as I don't miss and I "shoot good", it always worked for me. That's kind of the whole reason why I have trained and shot multiple competition disciplines for so many years and continue to do so. Training with a purpose and within context will whup a statistic in a fight every time.

 

[Kleanbore]

Graphs and statistics...I have yet to be in a violent encounter with either....Never had a statistic pull a knife or a gun on me.

What is your point?

 

[JeffG]

I agree. Redundancy for mechanical function, not amount of ammo, to an extent. I am a pessimist when it comes to mechanical function. I cannot help but feel the need for one in the magwell, and two on the belt; decades on patrol. CCW type carry usually winds up to be one reload.
My plan for high ammo expenditure during a serious social encounter, tends to have me moving toward a 2nd and third well supplied weapon in a bug out bag, or jungle clipped AR or AK, depending on my location or mode of transportation. I have Murphy's Law tee shirt and the stuffed panda. I don't go looking for trouble, but when trouble crosses my path it tends to come like a Mariachi band; loud and from an unexpected direction.
If that makes me a paranoid or "crazy" so be it. But I like to prevail, I don't like losing. Part of the problem about trouble, armed or ill mannered, is that a good percentage is in your presence, but aimed at someone else. Then I have to decide if I want to jump in, or fade and call the police; and am I prepared enough if it goes down twisted?

 

[JohnKSa]

Graphs and statistics...I have yet to be in a violent encounter with either.

The idea is that they can help you gain insight without having to actually get it from gunfight experience. It is to be hoped one would use graphs and statistics as an aspect of preparation to help improve one's understanding, rather than pulling them out like a roadmap during an actual violent encounter.

Never had a statistic pull a knife or a gun on me.

Never had a Tuesday spin the blue ratchet. Not sure why we're swapping nonsensical and irrelevant statements...

Of course you are correct--statistics don't carry weapons or attack people and nothing in the explanation of the graphs imply that they do. But they can provide useful insight at times.

...as long as I don't miss...

Never missing does simplify things a lot and the graphs don't provide any useful insight if one assumes that defenders never miss. Most people do miss, especially when being shot at. Given that reality, it can be useful/interesting to be able to get a feel for how a given hit rate probability will affect the ability to make a given number of hits with only a limited number of shots.

For example, one might think that a 5 shot pistol (a fairly common carry gun capacity) and a 30% hit rate (often quoted hit rate for LE shootings) will guarantee a decent probability of success in a scenario where the attacker needs to be hit at least twice to be neutralized. Turns out that that there's a better chance of failing to make 2 hits (53%) than succeeding given those assumptions.

That's kind of the whole reason why I have trained and shot multiple competition disciplines for so many years and continue to do so.

I agree 100%. However, not everyone understands the full value of increasing skill through competition and training and the graphs can help provide some insight in that arena too.

Going back to the example scenario, doubling the number of rounds available from 5 to 10, while keeping the 30% hit rate the same, actually provides a smaller amount of improvement (improves chances of success from 47% to 85%) than leaving the capacity at 5 and doubling the hit rate from 30% to 60% (improves chances of success from 47% to 91%).

 

[hdwhit]

JohnK Sa wrote:
...how a given hit rate probability will affect the ability to make a given number of hits...

But how does a shooter who only ever shoots at a range or in staged scenarios determine a realistic "hit rate probability"?

Or, looking at it another way, if someone assumes they need two hits to put their assailant out of action and they want to be certain (i.e. 100% chance of success) and they carry a pistol with seven rounds, then the table shows they need a Hit Rate Probability of 70%. How does someone that can hit their target 100% of the time at the range determine whether that at least as good as a Hit Rate Probability of 70% under stress?

 

[Creaky_Old_Cop]

What is your point?

My point is the over thinking and trying to "engineer" or "mathematize" a formula for fighting does nothing to increase efficiency or effectiveness. The only thing that does that is reality based training and that comes with blood, sweat, and dirt. Over my entire career, I considered the most dangerous place to be was near the brass and where command decisions on what we needed on the street, or how we should handle any exigency was dictated by a statistic. A statistic never rolled into 'da hood and did a drive by. Anything they couldn't invent a graph or a statistic to "expertly explain" was declared an anomaly and "removed for clarity".

(Removed Due To Sodium Content)

 

[hdwhit]

Kleanbore wrote:
It is important to understand that averages mean nothing.

I disagree.

If you meant that averages could not (or at least should not) be looked at to provide a definitive answer to the question, then I would certainly agree. But, to say that we must completely dismiss the statistical information gleaned from similar encounters is to ultimately reduce the answer to the question to a nothing more than a guess.

Unless we are going to choose how many rounds we carry by tossing dice or using Ouija board, then the decision how many rounds to have in a gun (or the decision to buy a gun capable of handling at least a certain number of rounds) has to be made on the basis of something. What type of scenario do you anticipate being in when you need a gun? How many attackers? What are they armed with? And so on.

If the "average" number of attackers in a particular self-defense scenario is three and the median number of bullets fired in similar encounters is seven, then it would be foolish to prepare to only deal with two attackers and carry a gun with only five rounds since it would mean that more than half the time you would run out of ammunition before you finished dealing with your assailant.

 

[JohnKSa]

But how does a shooter who only ever shoots at a range or in staged scenarios determine a realistic "hit rate probability"?

One could examine actual gunfight data to get a feel for what kinds of numbers are realistic and try to boil it down to a single representative number. Or one could assume that it falls into a range and look at the range of success probabilities that would result from that range of input assumptions.

My point is the over thinking and trying to "engineer" or "mathematize" a formula for fighting does nothing to increase efficiency or effectiveness.

Nothing in the graphs is a "formula for fighting". If that's what you think, then you have misunderstood everything in the thread starting from the very beginning.

As far as increasing a person's effectiveness, there is no claim that merely reading and understanding the graphs will make a person more effective or efficient gunfighter. But gaining an insight into the simplified probabilities that the graphs provide could help prevent a person from making a carry gun capacity choice that won't handle a scenario that they feel is reasonable. That would make them more effective.

For example, if a person wants to be prepared for a 2 attacker scenario where each attacker requires at least 2 hits for neutralization and the person assumes that a 50% hit rate is reasonable, they might be surprised to find that a 5 shot guns offers, at best, given those assumptions, a 19% chance of success. Obviously the actual real world results could be worse than that, but if the requirement is to make 4 hits with a 50% hit rate with only 5 shots on tap, the odds won't be better than that.

Is the person more efficient and effective for knowing that? No. But if they decide that they're not happy with those odds and increase the capacity of their carry gun, that could definitely make them more effective.

Does that eliminate the need for training. Not at all. In fact, as I demonstrated in the last post, it's easy to see from the graphs that increasing the skill level of the shooter provides a big benefit.

The only thing that does that is reality based training and that comes with blood, sweat, and dirt.

It's probably good that you make the point. I would like to think that nobody out there thinks that reading some graphs will make them a better gunfighter, but who knows.

...where command decisions on what we needed on the street, or how we should handle any exigency was dictated by a statistic.

Your point is sound but not especially relevant. The graphs are not intended to (nor do I see how they could) provide any insight into how exigencies on the street should be handled.

Anything they couldn't invent a graph or a statistic to "expertly explain" was declared an anomaly and "removed for clarity".

The numbers have not been tweaked or adjusted and the calculations are accurate and (although it may not seem that way) very straightforward in terms of standard probability mathematics. The assumptions are very simple and clearly stated. There's no attempt to make the numbers say something they don't or cover up something they do say.

...the decision how many rounds to have in a gun (or the decision to buy a gun capable of handling at least a certain number of rounds) has to be made on the basis of something. What type of scenario do you anticipate being in when you need a gun? How many attackers? What are they armed with? And so on.

Exactly correct. The graphs do not get into the weapons of the attackers or the specific scenario, they focus on how many hits are required for success, how many rounds are available to solve the problem, and an assumed hit rate. A person can use the graphs to get a feel for how any of those variables affects the probability of "success" as defined by making at least the number of required hits. The goal is precisely to provide a more constructive way to make decisions than guessing.

If the "average" number of attackers in a particular self-defense scenario is three and the median number of bullets fired in similar encounters is seven, then it would be foolish to prepare to only deal with two attackers and carry a gun with only five rounds since it would mean that more than half the time you would run out of ammunition before you finished dealing with your assailant.

The graphs help to provide insight into just that kind of analysis. But instead of just saying "more than half" (which may or may not be accurate) you can actually get fairly precise numbers which act as a sort of "best case scenario". If the "best case scenario" numbers are dismal, then maybe it's time to rethink--right?

 

[JeffG]

My point is the over thinking and trying to "engineer" or "mathematize" a formula for fighting does nothing to increase efficiency or effectiveness.

Bingo. Spot on.

 

[herrwalther]

Most gun experts ("self-proclaimed" or otherwise) recommend carrying at least one reload when carrying. Statistically speaking, you are likely to end a defensive gun use encounter with 3-5 shots. If you have to fire at all. There are many cases where bad guys even being presented with a firearm cause them running. The reason for the reload is often stated as redundancy and not just additional rounds for an extended gun fight. A reload, either for a revolver or semi-auto, weights significantly less than carrying a second firearm for those who would rather "NY style" carry with 2 (or more) firearms.

Personally I carry one spare magazine. With both my double stack and single stack firearms. It is for both redundancy in case of malfunction and for total round count. In my line of work, I get death threats on almost a daily basis. So I am okay with carrying 7 extra rounds on my single stack and 12 (usually) more on my doubles.

 

[JeffG]

The free radicals, if you will, of any fight occur exponentially because nothing is constant. Number of assailants, drug or alcohol content, mental stability , military background of any of the actors... having a flat tire..... or a sinus infection. So little of these factors can be measured and quantified, you can't predict them. Beyond sterilized numbers like shots fired and distances of other people's fights...nothing will accurately predict what is going to happen.

 

[JohnKSa]

Bingo. Spot on

Of course it is. It's a true statement and an insightful observation. But totally irrelevant to the point of the graphs.

The free radicals, if you will, of any fight occur exponentially because nothing is constant. Number of assailants, drug or alcohol content, mental stability , military background of any of the actors... having a flat tire..... or a sinus infection. So little of these factors can be measured and quantified, you can't predict them. Beyond sterilized numbers like shots fired and distances of other people's fights...nothing will accurately predict what is going to happen.

All exactly correct. But not especially relevant.

The graphs do not attempt to provide a high-fidelity gunfight simulation. They only provide insight into only three variables that affect "success".

The graphs do not attempt to predict the number of assailants or how resistant to pain or injury they may be. They do not attempt to predict their abilities or background. They do not attempt to quantify or predict the fitness of the defender or the attackers. They do not attempt to predict or provide insight into the distances at which gunfights take place.

What they do is the following:

If one ASSUMES a particular hit rate and ASSUMES a particular capacity and ASSUMES a particular number of hits required for "success" then the graphs provide the probability of "success" as defined by achieving the required number of hits.

Sorry to disappoint those who think it's possible to turn a gunfight into a 2 dimensional plot. Sorry to disappoint those who think that a spreadsheet calculation can predict how many assailants will attack or what their background and state of chemical alteration will be.

None of that is possible. But what is possible is to provide some insight into some basic probabilities that might actually be useful to understand.

The first post is key to understanding how this all works. If you just jump in with both feet and assume what's going on without trying to figure it out first, it's not going to be productive for anyone.

Here's an analogy for what's going on so far on this thread:

John: "Hey, look at this Jim, I invented a little electronic computer that adds, multiplies, subtracts and divides!"

Jim: "That's stupid, computers will never be able to replicate human intelligence. Don't you realize how complicated that would be?"

John: "Yeah, that would be very difficult and I'm not trying to do that. But look, if you need to know what 2198397 times 128709345 is, it tells you right away and it never makes a mistake. Isn't that useful compared to having to work it out by hand and maybe screwing up the calculation?"

Jim: "People are super complicated. And what about human emotion! It's impossible to duplicate that with circuits. You must be a total idiot!"

John: "Ok..."

 

[NIGHTLORD40K]

As many as I will grab every time and not leave them (and the gun) at home because it is too heavy, bulky, or inconvenient. So for me that's 7+1. I figure that's enough to let me fight my way back to my rifle (which is never very far), or aquire one of the bad guys weapons, and if I need more than that, well, I'm prolly screwed anyway.

 

[Creaky_Old_Cop]

But how does a shooter who only ever shoots at a range or in staged scenarios determine a realistic "hit rate probability"?

Or, looking at it another way, if someone assumes they need two hits to put their assailant out of action and they want to be certain (i.e. 100% chance of success) and they carry a pistol with seven rounds, then the table shows they need a Hit Rate Probability of 70%. How does someone that can hit their target 100% of the time at the range determine whether that at least as good as a Hit Rate Probability of 70% under stress?

But how does a shooter who only ever shoots at a range or in staged scenarios determine a realistic "hit rate probability"? How does a so-called shooter who does NOT "ever shoot at a range" or in "staged scenarios" determine a realistic hit rate probability? It's damned sure not from staring at a graph and a computer screen. Hence, the blood, sweat, dirt, burned powder, lead, realistic training, and WORK that must be put in to develop a set of skills that can be relied upon to give one the best potential for efficient, effective accuracy in any defensive situation.

A graph would never tell me what my realistic hit potential is/was in a shoot house going against an opposing force of other officers with simunitions (Owie Rounds). A graph would never tell me what my realistic hit potential is/was in a USPSA IDPA, or Police Combat match...only getting out there, burning powder, lead, sweating, and eating dirt will do that.

BUT...we're talking about the difference between shooters and "enthusiasts" who don't do silly stuff like actually shoot/train/practice or compete. Someone who "shoots intellectually" which is the best analogy I can come up with for someone who does't eat range dirt often, and burns a box of ammo with their buddies every once in a while versus a shooter will never see anything but a dismal hit potential, regardless of the exigency they are facing. Similarly, officers who "qualify" at the determined interval and don't actually get out and train and eat range dirt are going to be in the same boat. Officers and non LE competitors and true "students of weaponcraft" and defensive shooting combine the intellectual with the range dirt, and with a heavier emphasis on the range dirt.

Or, looking at it another way, if someone assumes they need two hits to put their assailant out of action and they want to be certain (i.e. 100% chance of success) and they carry a pistol with seven rounds, then the table shows they need a Hit Rate Probability of 70%. How does someone that can hit their target 100% of the time at the range determine whether that at least as good as a Hit Rate Probability of 70% under stress? Number one...I never assume anything in a fight other than "I have to get efficient, effective hits, right now, otherwise there is going to be a hole in my meat wrapper". How do I get to the level of confidence to sift the "theology of bang" down to that one statement? See again...eating range dirt, training, practice, competition to add stressors into your training in context.

I would never assume I needed any number of hits on an assailant. The one thing I do know is that one might not be enough, and 437 might not be too many. So somewhere between one and infinity are the rounds you will need. So, you use graphs and statistics to determine how badly you suck on the range where you don't spend any time then you consult a statistic to tell you how many boolits you need what kind of gun you need....OR....you use common sense, logic, and reason to determine that two spare mags (regardless of the full size fighting handgun I am carrying), will be enough to deal with an immediate threat, balance the load of my defensive tools, and handle any mechanical failures that come along because I HAVE eaten all that range dirt, trained, practiced, competed, and built a level of skill over the years where I am confident in my ability to get the efficient, effective hits I need when I need to get them.

Rob Leatham (whom I have known and shot with/against since before he was famous) has a t-shirt that reads "The callouses on my fingers are from the trigger, not the keyboard".

Blood, sweat, range dirt, burnt powder, splashed lead....

Sweaty...dirty...smelly...Odor of burnt powder and GSR all over me...and a big assed nasty "Jesus Hand" from actually shooting, training, practicing, competing, and building skills. I'll keep burning 1000-2000 primers a week and putting lead on targets and eschew the statistics.

 

[JohnKSa]

See again...eating range dirt, training, practice, competition to add stressors into your training in context.

All good information, all irrelevant. I really don't know how someone could read through the first post and come away with such a mistaken impression of what's going on with the graphs.

...two spare mags (regardless of the full size fighting handgun I am carrying), will be enough to deal with an immediate threat...

In case it's not obvious, a person who carries pretty much the max ammo load they can manage isn't going to get much out of the graphs. The people who might actually learn something from them are the ones who are thinking about minimizing the capacity they can get away with. The graphs can provide some useful insight into why that might not be a good idea for those who might not understand so easily otherwise.

They can also provide some insight for people who do carry small ammo loads--it provides some perspective on a what kind of capability they will have (or more accurately--won't have) in a sort of "best case scenario".

A graph would never tell me what my realistic hit potential is/was in a shoot house going against an opposing force of other officers with simunitions (Owie Rounds).

The graphs are certainly not intended to do that, nor could one use them for that purpose.

Number one...I never assume anything in a fight other than "I have to get efficient, effective hits, right now, otherwise there is going to be a hole in my meat wrapper".

The assumptions made to use the graphs are not made "in a fight" and are not based on, nor should they affect the mindset of a defender during a fight.

I would never assume I needed any number of hits on an assailant.

The graphs aren't intended to provide insight into how many hits one needs for an assailant nor to predict it. Nor are they able to do so. What they do is allow a person to look at how a changing the number of hits required will change the probabilities of running out of ammo before getting the required number of hits.

So somewhere between one and infinity are the rounds you will need.

Yup, that is correct. But it is not particularly insightful. It is possible to gain more insight and narrow the range somewhat by using the graphs. They can't predict how many you will need to succeed--nothing can do that--but they can give you some insight into how many rounds you need to reduce your chances of failing due to insufficient capacity to an acceptable level.

I'll keep burning 1000-2000 primers a week and putting lead on targets...

An excellent strategy and nothing in this thread or the graphs suggests otherwise. In fact, they can provide some insight into how much increased skill can improve the odds of surviving a gunfight.

...eschew the statistics.

Of course, you're welcome to do so. I wish you had taken the time to actually understand their purpose and how they work, but I suppose what I wish is neither here nor there.

 

[grampajack]

There's definitely no such thing as too much ammunition. Personally, it always pisses me off when people say things like, "If you need more than X then you're not training hard enough," or, "If you need more than X then you've already lost." Etc. and so forth...

What is it, like half of all robberies involve multiple attackers? And how many of those are armed? And how many rounds does the average cop need to stop a single threat? The only answer to the question of how many rounds to carry is, "As many as you can."

I will qualify that, though, by adding that a round in the gun is worth ten rounds in backup mags (IMHO of course). In other words, I would rather have a G19 with no backup mags than a G26 with a whole belt full of them.

 

[JohnKSa]

Maybe this is an easier way to think of what the graphs do.

They can't tell us if we will succeed. They can provide insight into scenarios where success is very improbable. They can give us an idea of what kinds of scenarios (based on the three parameters of hit probability, number of shots required and capacity) are "workable" and which ones aren't. They allow us to vary those three parameters to see how they affect the workability of the scenario.

If you look at the case where the number of hits required is 1, the capacity is 15 and the hit rate is 90%, the chances of "success" (making your 1 hit before the magazine runs dry) are essentially 100%. Does that mean you are guaranteed to survive a gunfight based on that scenario? NOT AT ALL! There are all kinds of way you could still be killed. Maybe your gun jams, maybe the guy hits you in the brain with his first shot before you can even fire. Maybe you slip and fall and injure yourself and end up a sitting duck. All the graph tells you is that if you fail to "win" the gunfight in that scenario, it's very unlikely that failure was the result of an unworkable combination of capacity, hit rate and the number of hits required. Something else was likely the cause of the failure.

Now let's look at the case where the number of hits required is 6, the capacity is 7 and the hit rate is 30%. We can see the chances of success are very close to zero from the graph. This tells us something very important. It tells us that we have set up an unworkable scenario. Even if we get to expend all our ammunition and everything else goes perfectly, the odds of succeeding in making all the hits we need are just about nil. If we think that this is a scenario we want to prepare for, then the graphs tell us that a 7 shot gun is a very poor choice. Well, how could we improve the situation? The graphs let us change the capacity to 15 to see if different hardware might get us out of the "doomed to fail" situation.

Unfortunately that only improves our chances of making all the hits we need before hitting empty to about a 3 in 10 chance of success--and that's if everything else goes perfectly. Still pretty bad. Now we should start thinking that maybe a person with the skill level to only make 30% of their shots in a gunfight is in a really, really bad situation if they need to make 6 hits, no matter how much ammo they carry and even if everything else goes perfectly. We've gained some valuable perspective about the limitations imposed by our skill level and equipment.

 

[Officers'Wife]

This sort of question is outside of my experience so I must consider the advice of my ancestors before me. As per my late uncle- when you are prone in the mud peeing your drawers while bullets are flying over your head and splashing mud in your eyes you will always find you should have brought another magazine. Or that of my grandfather who's pithy advice was simply if you find you have run through your clips you either started shooting too soon or shouldn't have been shooting at all.

 

[Kleanbore]

My point is the over thinking and trying to "engineer" or "mathematize" a formula for fighting does nothing to increase efficiency or effectiveness.

No one is trying to "a 'engineer' or 'mathematize' a 'formula for fighting'' "

The only thing that does that is reality based training and that comes with blood, sweat, and dirt.

True fact.

 

[Kleanbore]

If you meant that averages could not (or at least should not) be looked at to provide a definitive answer to the question, then I would certainly agree.

Neither averages nor any other statistical measures or predictions can provide a "definitive answer to the question". See Post 1.

But, to say that we must completely dismiss the statistical information gleaned from similar encounters is to ultimately reduce the answer to the question to a nothing more than a guess.

No one has said as much, but there are very few actual data to be analyzed, and a great many variables.

But I would never make a predictive decision of any kind on the basis of averages, unless I were in the insurance business.

Unless we are going to choose how many rounds we carry by tossing dice or using Ouija board, then the decision how many rounds to have in a gun (or the decision to buy a gun capable of handling at least a certain number of rounds) has to be made on the basis of something.

Yes. How about informed judgment?

The analysis John has presented can help us think through the possibilities, and illustrate, perhaps, how many long-held two not water, but they cannot show us the "right" decision.

If the "average" number of attackers in a particular self-defense scenario is three and the median number of bullets fired in similar encounters is seven, then it would be foolish to prepare to only deal with two attackers and carry a gun with only five rounds since it would mean that more than half the time you would run out of ammunition before you finished dealing with your assailant.

And it tells us nothing more. What do we do with that nugget of information?

 

[Elkins45]

I makes me sad that so many gun people feel the need to instinctively adopt an anti-intellectual attitude whenever anyone attempts to use statistics or reason as a lens through which to analyze gun stuff.

 

[JohnKSa]

In all fairness, there is a lot of BS out there masquerading as something amazing. I can understand why someone who incorrectly thinks this calculation and the graphs are being billed as a gunfight simulator would get pretty upset about that. I can also understand why a person who believes that the calculations are intended to replace training or are intended for use as a reference to rely on in a gunfight would be scornful.

This analysis provides some very basic insight into an aspect of self-defense firearm choice that is otherwise not simple to understand. People have a hard time dealing with probabilities intuitively--this is part of why casinos make money--so sometimes it helps to have the information laid out in a usable format.