How Many Rounds to Carry

Status
Not open for further replies.
JohnKSa said:
Of course it is. It's a true statement and an insightful observation. But totally irrelevant to the point of the graphs.All exactly correct. But not especially relevant.
Click to expand...

Sorry to be so irrelevant. Predicting the numbers of assailants and ability to hit them under unspecified conditions is impossible. The factors leading to the expectation of increased ammunition need, would also lead one to avoid those areas and people. Except in combat defensive positions, predicting and supplying ammo is an elusive quantity. Carrying X amount of ammo would be qualified by experience, threat assessment, paranoia, and the ability to conceal and carry it.
 
Sorry to be so irrelevant.
Click to expand...
No need to apologize. When I created the graphs, I thought that the point of the graphs and their function would be easy to understand but I was mistaken.
Predicting the numbers of assailants and ability to hit them under unspecified conditions is impossible.
Click to expand...
Agreed. However the graphs won't and can't do either of those things and aren't intended to.
 
Keep in mind that anytime you make up a statistical model most if not all will expect the results to say more than intended. My limited understanding of your work is that the more you hit the better chances of success and the better you aim the better your chance for a hit. With those limits (again in my limited understanding) the number of assailants, the pressure or even equipment malfunction isn't relevant, only "hits" and rounds fired. While the math is interesting, the conclusion is pretty obvious through common sense. That doesn't negate the usefulness of the graph(s) though.
 
Officers'Wife said:
While the math is interesting, the conclusion is pretty obvious through common sense.
Click to expand...
Well, it wasn't really obvious to me. The extremely low likelihood of success that one would be afforded with a five shot handgun ( based on any realistic set of assumptions) is much lower than I had ever contemplated.
 
. With those limits (again in my limited understanding) the number of assailants, the pressure or even equipment malfunction isn't relevant, only "hits" and rounds fired.
Click to expand...
Right. The assumptions are that all the shots available fire without issue. No malfunctions, no getting killed before you empty the gun, no degradation of accuracy due to being injured or stressed.

It sets up a sort of best case scenario and then allows the user to look at how the probabilities work out for that scenario.

For example, if I were to assume that I had 6 shots and needed to make 3 hits with an assumed hit rate of 40%, I could look at the graphs and determine that if everything went exactly per the assumptions the chances of making the required 3 hits with 6 shots are about 45%.
Well, it wasn't really obvious to me.
Click to expand...
I'll also admit to being surprised at the improbability of making several hits with a small number of shots and hit rates based on LE gunfight statistics. I originally worked out the numbers for myself and when I saw the results, I thought others might be interested.

I think part of the issue is that probabilities aren't always intuitive. It wasn't hard for me to understand that making 4 hits with 6 shots requires a fairly good hit rate, but I was surprised to find that with a 30% hit rate (a commonly quoted hit rate probability from LE gunfights), the chances of success are only 7 out of 100.
 
Kleanbore said:
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.

View attachment 761521
View attachment 761522
Attached Images
View attachment 761523 S=1_Cap_x=HR.jpg (231.1 KB, 131 views)
View attachment 761524 S=1_HR_x=Cap.jpg (228.5 KB, 126 views)
__________________


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.

View attachment 761525
View attachment 761526
Attached Images
View attachment 761527 S=2_Cap_x=HR.jpg (204.5 KB, 115 views)
View attachment 761528 S=2_HR_x=Cap.jpg (193.0 KB, 114 views)
__________________


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.

View attachment 761529
View attachment 761530
Attached Images
View attachment 761531 S=3_Cap_x=HR.jpg (221.5 KB, 115 views)
View attachment 761532 S=3_HR_x=Cap.jpg (208.6 KB, 115 views)
__________________


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.

View attachment 761533
View attachment 761534
Attached Images
View attachment 761535 S=4_Cap_x=HR.jpg (227.4 KB, 115 views)
View attachment 761536 S=4_HR_x=Cap.jpg (213.8 KB, 117 views)
__________________
Click to expand...


Thanks Kleanbore for sharing this and JohnKsa for putting it together, I found it helpful.

I sometimes carry a 5-shot smith snubby and as long as I am comfortable relying on the statistical probability (not addressed in your charts ;-) ) that just producing the weapon will end most encounters I am good to go.

But, the charts made it pretty clear that IF I ever did have to fire the gun at an assailant (especially if there were multiple assailants) 5 shots would not provide a probability of success which I am (subjectively) comfortable with (say 80% or better of making the hits), assuming a hit probability I am (subjectively) comfortable relying on in a gun fight situation (say 30-40% - I'm an IPSC "B" shooter in 3 divisions but can't assume even that moderate level of performance!). This seems to be the main take-away from the charts and provides a good visual explanation of those facts. Not so comfortable with my Smith anymore.
 
Last edited:
Yes, in my effort to jump in with my opinions, (I know, opinions are like butt holes) I did forget to thank Kleenbore for the post. Great post!
 
After staring at the charts for 15 minutes I finally remembered why I failed algebra in high school and never attempted college. The experience also reminds me why I don't reload. And yes, I'm honest enough to admit both.
 
I sometimes carry a 5-shot smith snubby and as long as I am comfortable relying on the statistical probability (not addressed in your charts ;-) ) that just producing the weapon will end most encounters I am good to go.
Click to expand...
That is correct. The charts are specifically about making a required number of hits. It is certainly true that many self-defense gun uses (the majority, actually) are resolved without the need to fire the gun, or at least without the need to score a hit.

If a person wishes to rely purely on the deterrent factor of the firearm, then the charts are not going to be helpful. Of course, in a situation like that, the entire concept of capacity becomes moot.
Not so comfortable with my Smith anymore.
Click to expand...
I think a lot of folks got the idea that I'm trying to push people to carry different self-defense firearms, but that's not it at all. It was simply provided as a way to help people to get a feel for probabilities that aren't especially intuitive.

I did not instantly change to different carry guns after I looked at the results of the calculations. The main change was in my perspective about what kind of a realistic capability a subcompact carry gun provides.
 
Last edited:
John and Kleanbore,

Thank you for the obvious time and effort in getting this pulled together.

I do not understand the pushback on the graphs in this discussion. The message to this engineer is that 'success' is proportional to ammunition capacity. What I learned is how tightly it is correlated. Good work there.

At one level, the message is "Mo is Better", right?
 
Just being honest,if i'm carrying my Bulldog .44 spl. revolver, it's loaded an five extra rounds in my pocket.If i'm carrying my M&P 40 Shield 6+1 and extra mag.with 6 rounds.
 
johnmcl said:
John and Kleanbore,

Thank you for the obvious time and effort in getting this pulled together.

I do not understand the pushback on the graphs in this discussion. The message to this engineer is that 'success' is proportional to ammunition capacity. What I learned is how tightly it is correlated. Good work there.

At one level, the message is "Mo is Better", right?
Click to expand...

Not so much that "more is better" than your bullets aren't nearly as destructive as you would like to think they are. Too many have bought into the Hollywood theme that a single shot to the chest is going to end the fight immediately, the graph just backs up what my Gramps told me - "you best try just to make the other guy consider he may have made a bad enough mistake to want to change his mind."
 
For what it is worth, I found the article informative and interesting and I thank the author who took the time to put it together.

With that said, I have been in actual gunfights. Excluding military action, the number is eleven. Eleven serious social situations where someone was looking to kill me and/or fellow agents. None of these were raid situations, but nitty gritty close quarters shootings. I have been shot by six different people (excluding military action). Once with a 12 gauge sawed off double barrel, once with a 9MM, twice with snub nosed .38 specials, once with a .22 zip gun, and once by accident (hunting) with a .22 rifle by my first wife and the only time I did not shoot back. So, I know a little bit about gun fights.

When I was on the job, I routinely carried four guns, the primary being a .45, with the backups of lesser size and caliber. My primary reason for that many guns was based in the nature of the assignment. There was a high probability that I would be searched and relieved of my primary gun at times, and sometimes (if they were good) my second gun. The third and fourth guns were small and well hidden to try to retain some firepower even after a search.

All of that disclosed, I carried only one extra magazine for my primary and no extra rounds for any of the backup guns. Today, no longer on the job, I carry a SA XDs in 45 ACP and carry two extra magazines. I am flirting with a Bond Arms Bullpup as a primary which would cause me to go from a .45ACP to a 9MM. When I carry it, I carry four extra magazines because of the caliber. And no, I am not interested in hearing how much better 9MM ammo is today, unless you have actually used it in a gun fight or been shot by it.
 
ChanceMcCall said:
For what it is worth, I found the article informative and interesting and I thank the author who took the time to put it together.

With that said, I have been in actual gunfights. Excluding military action, the number is eleven. Eleven serious social situations where someone was looking to kill me and/or fellow agents. None of these were raid situations, but nitty gritty close quarters shootings. I have been shot by six different people (excluding military action). Once with a 12 gauge sawed off double barrel, once with a 9MM, twice with snub nosed .38 specials, once with a .22 zip gun, and once by accident (hunting) with a .22 rifle by my first wife and the only time I did not shoot back. So, I know a little bit about gun fights.

When I was on the job, I routinely carried four guns, the primary being a .45, with the backups of lesser size and caliber. My primary reason for that many guns was based in the nature of the assignment. There was a high probability that I would be searched and relieved of my primary gun at times, and sometimes (if they were good) my second gun. The third and fourth guns were small and well hidden to try to retain some firepower even after a search.

All of that disclosed, I carried only one extra magazine for my primary and no extra rounds for any of the backup guns. Today, no longer on the job, I carry a SA XDs in 45 ACP and carry two extra magazines. I am flirting with a Bond Arms Bullpup as a primary which would cause me to go from a .45ACP to a 9MM. When I carry it, I carry four extra magazines because of the caliber. And no, I am not interested in hearing how much better 9MM ammo is today, unless you have actually used it in a gun fight or been shot by it.
Click to expand...

That’s quite a mix of good and bad luck, and probably quite a few lessons learned along the way. Have you ever thought about writing a book?
 
psyopspec said:
That’s quite a mix of good and bad luck, and probably quite a few lessons learned along the way. Have you ever thought about writing a book?
Click to expand...

No. I'm in a totally different field today so I don't see a point to doing so. The other thing is I have been out of law enforcement for a very long time and much of what I could share is very out of date. I was also in a very specialty area that is also out of date. The use of firearms by covert or undercover personnel is still much the same, but there are some very knowledgeable instructors at FLETC who have the experience and do a very good job of training people headed into those jobs.

If I have a gripe in this area, it is that some very good instructors have either a military background or a background in law enforcement with an emphasis on belt guns and the mindset of backup being nearby. I would contend that that kind of experience colors both the thinking and the training delivered, and often, not in the best interests of the civilian seeking training.

Here is my best tip for civilians and retired personnel: If a robber comes into the gas station or Seven 11 and you are armed, your first thought should be to hide, not confront. You are not a LEO. Protect yourself and your family if they are there only if hiding doesn't help. You are not being paid nor required to try to be John Wayne or Dirty Harry. Don't believe all the Hollywood crap about being shot. It may not hurt very much while it is happening, but if you are fortunate enough to live, it will hurt a hell of a lot, for longer than you think. While you are trying to reclaim your physical health, your net worth is under attack by the medical profession, the loss of income, and perhaps by attorneys.

Point Two: I have read all the data about magic .380 and 9MM ammo. Ballistic Gel serves a purpose, but not the one that relates to stopping power. If someone want to prove a point to me and, I suspect others who have been there, go to some other country and risk the wrath of the media and the ASPCA, and Green Peace, and whoever else will scream and line up a couple of hundred full grown pigs that have been coked up and start shooting them with different rounds and measure the results. (Do it in a country where people are hungry and give them the meat. They won't care you shot it up and you will have a charity tax write-off.)

Share results of stopping power, not lethality. Hell I can kill a 300 pound boar with a North American .22LR revolver. The real question is, "Will he stop attacking me before he does me any damage?", which is a far different question. I seriously doubt if I could get many advocates of these new magic rounds to agree to stand in a fenced in run, with a chemically enraged boar at the other end (30 feet) with their magic pistol and even 10 rounds of ammo in their gun.

Point Three: Civilian concealed carriers are usually caught by surprise and cannot normally count on backup. They are going to have to solve the problem themselves or suffer the consequences. Even worse, someone else may shoot them thinking they are the bad guy. Some of the training scenarios I have seen and the positions they are teaching people to take are ridiculous for non uniformed personnel.

OK. That is as close as I will come to a book on the subject of what I think is important regarding civilians who choose to carry a gun. The other stuff I would not like writing about. I have read some of the stuff that other guys I respected a lot wrote, and in many ways, I felt it diminished them. Not my thing.
 
ChanceMcCall said:
No. I'm in a totally different field today so I don't see a point to doing so. The other thing is I have been out of law enforcement for a very long time and much of what I could share is very out of date. I was also in a very specialty area that is also out of date. The use of firearms by covert or undercover personnel is still much the same, but there are some very knowledgeable instructors at FLETC who have the experience and do a very good job of training people headed into those jobs.

If I have a gripe in this area, it is that some very good instructors have either a military background or a background in law enforcement with an emphasis on belt guns and the mindset of backup being nearby. I would contend that that kind of experience colors both the thinking and the training delivered, and often, not in the best interests of the civilian seeking training.

Here is my best tip for civilians and retired personnel: If a robber comes into the gas station or Seven 11 and you are armed, your first thought should be to hide, not confront. You are not a LEO. Protect yourself and your family if they are there only if hiding doesn't help. You are not being paid nor required to try to be John Wayne or Dirty Harry. Don't believe all the Hollywood crap about being shot. It may not hurt very much while it is happening, but if you are fortunate enough to live, it will hurt a hell of a lot, for longer than you think. While you are trying to reclaim your physical health, your net worth is under attack by the medical profession, the loss of income, and perhaps by attorneys.

Point Two: I have read all the data about magic .380 and 9MM ammo. Ballistic Gel serves a purpose, but not the one that relates to stopping power. If someone want to prove a point to me and, I suspect others who have been there, go to some other country and risk the wrath of the media and the ASPCA, and Green Peace, and whoever else will scream and line up a couple of hundred full grown pigs that have been coked up and start shooting them with different rounds and measure the results. (Do it in a country where people are hungry and give them the meat. They won't care you shot it up and you will have a charity tax write-off.)

Share results of stopping power, not lethality. Hell I can kill a 300 pound boar with a North American .22LR revolver. The real question is, "Will he stop attacking me before he does me any damage?", which is a far different question. I seriously doubt if I could get many advocates of these new magic rounds to agree to stand in a fenced in run, with a chemically enraged boar at the other end (30 feet) with their magic pistol and even 10 rounds of ammo in their gun.

Point Three: Civilian concealed carriers are usually caught by surprise and cannot normally count on backup. They are going to have to solve the problem themselves or suffer the consequences. Even worse, someone else may shoot them thinking they are the bad guy. Some of the training scenarios I have seen and the positions they are teaching people to take are ridiculous for non uniformed personnel.

OK. That is as close as I will come to a book on the subject of what I think is important regarding civilians who choose to carry a gun. The other stuff I would not like writing about. I have read some of the stuff that other guys I respected a lot wrote, and in many ways, I felt it diminished them. Not my thing.
Click to expand...

Thanks for sharing more. That’s very well-informed and interesting. If you ever change your mind about the book, shoot me a PM. I work in a part of the publishing industry, producing books through a series of interviews for people who don’t have the time, inclination, or skill to write.

Can I ask, who were some of the guys you respected that published? I think it’s easy to judge certain aspects of any story, but I’ve gotten a lot out of reading books by the likes of Jim Cirillo and others. That kind of writing is not a primary source for tactics, but can be an informative glimpse (w/ a grain of salt) into the fighting mindset and history of certain times/places/professions.
 
ChanceMcCall said:
No. I'm in a totally different field today so I don't see a point to doing so.
Click to expand...
What you are doing today is is irrelevant. A book would be about your claims regarding the past.

ChanceMcCall said:
The other thing is I have been out of law enforcement for a very long time and much of what I could share is very out of date
Click to expand...
True also with and Jelly Bryce and Jim Cirillo..

ChanceMcCall said:
I was also in a very specialty area that is also out of date.
Click to expand...
That didn't stop jim Cirillo.

ChanceMcCall said:
Ballistic Gel serves a purpose, but not the one that relates to stopping power.
Click to expand...
"Stopping power" with a handgun? Come now!
 
If you have been in 11 gunfights, then I think you should produce some evidence that proves that. That is quite a lofty claim, and frankly, is pretty hard to believe. So, put up or shut up on that, friend.
 
Concur. Anonymous internet user claims have zero credibility with me. I know, have met, otherwise been acquainted with or heard of many, many law enforcement officers who've been in one gunfight (and we're assuming this is within the U.S., right?) ... and we're talking 20 - 30 year careers here. But only a relative few who've been in more than one gunfight and that's rare as hell ... those who've been in multiple gunfights have pretty much achieved legendary status -- we know who they are -- and they're sure not anonymously posting on the internet.

This poster's sig line reads: I mistrust any advice on tactics, guns for defense, and caliber of ammo from anyone who has not actually been in a real gunfight.

Myself, I got a lot of good advice on this stuff in the military and law enforcement from a number of folks who'd never actually been in a real gunfight -- but that knowledge was hard-earned and came from those who had been, never had any reasons not to trust that advice. I just mistrust folks promoting themselves as having been in these situations and expecting us to believe that when it's totally unverifiable.

Eleven, though? Gecko45, is that you?
 
Status
Not open for further replies.

Similar threads

JohnKSa
  • Locked
Thoughts on Multiple Assailants, Hit Rate & Capacity
2 3 4 5 6 7
Replies
172
Views
12K
Prosser
P
george burns
  • Locked
How many rounds should your carry gun have loaded in it?
2 3 4 5
Replies
122
Views
10K
OldTengu
OldTengu
T
  • Locked
how many rounds will a guy need?? urban combat...
2
Replies
43
Views
2K
woodybrighton2
W
mcb
  • Locked
Momentum vs Kinetic Energy visualized, no mention of lethality
2 3
Replies
66
Views
4K
mcb
mcb
E
  • Locked
A Hail of Bullets, a Heap of Uncertainty - NY Times
Replies
2
Views
534
Cosmoline
C
Back
Top