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)
__________________