Hand Length to Gun Fit: A Case Study: Analysis and Conclusion (Part 3)

[RJ]

There is no industry wide, universally recognized sizing system for handguns, akin to clothing (S, M, L, etc.), to determine one’s pistol “Size”. In 2023, new handgun owners, in particular those with smaller stature, are entering the marketspace in increasing numbers. Historically, handguns have been sized for males, and very commonly selected based on large capacity for duty use.

Because of these two factors, today’s prospective pistol purchaser may end up buying a gun which is unlikely to meet their needs, due to inadequate trigger reach.

This study sought to determine a way to numerically evaluate gun fit, based on hand size, to reduce this risk.

The study is posted in three Parts:

Part 1: https://pistol-forum.com/showthread....-Size-(Part-1)

Part 2: https://pistol-forum.com/showthread....-Size-(Part-2)

This thread is Part 3. When completed, Part 3 will contain the Study Abstract, Analysis, Postulations, Conclusions, as well as Hand and Gun Tables.

Abstract

In Part 1, Hand Size among the study population was surveyed. Hand Sizes were analyzed and placed into seven proportionally sized brackets: XS, S, M, M/L, L, XL and 2XL, scaled to the 5% and 95% Hand Size centile. In Part 2, the study surveyed Gun Size, defined as Grip Circumference, owned by the study population. The study postulates that Gun Size can be scaled based on Hand Size, using the same proportions. Gun Sizes were therefore also placed into seven brackets, scaled to the 5% and 95% Gun Size Centile, but using the proportions of Hand Size.

A numerical method was thus devised to allow pistol users to select a gun, based on where their Hand size sits, within Gun Sizes.

The method consists of first measuring your Hand Size, to obtain your Gun Size. Numerical ranges of Hand Sizes are specified, and provided in the Hand Table. First, enter the Hand Table with your hand size, to determine your Gun Size. Second, consult the Gun Table. Here, commonly available Guns, grouped by Gun Size, are provided as sizing examples. Use the Gun Table to evaluate the fit of a specific gun, using the Grip Circumference, against your hand size. Selecting a Gun Size at, or below, your Hand Size, should result in an adequate trigger reach.

Using this method, users can thus select a Gun, or range of Guns, which will result in a reasonable expectation of a good fit, in the same manner you enter a clothing store, knowing your size, to select a shirt or pair of shoes. Due to the wide variation in hand dimensions, grips/stocks widths, trigger configuration, etc., a proper fit with adequate trigger reach is only a starting point. The user must evaluate their performance, in live fire, from guns they are considering, in order to make an ideal selection.


Subsequent posts in this thread will contain additional material, such as Analysis, Postulations, Conclusions, as well as Hand and Gun Tables, as they are completed. I genuinely appreciate all who took the time to respond to this study. Thank you!

[RJ]

Analysis – Part 1

Information on Hand Size for the study population was gathered in Part 1. The primary purpose of Part 1 was to determine if Hand Size was generally correlated with Glove Size (it was), and to provide data for later use.

MIL-STD-1472D, "Human Performance Engineering", commonly applied to Aerospace programs, was selected by the Author as the benchmark for the definition of anthropometric data, specifically “Hand Size”. MIL-STD-1472D defines Hand Size as the distance from the base of the palm to the tip of the middle finger (Item 57. in the illustration below).


MIL-STD-1472D, Figure 27.


As of this post, 25 participants responded in Part 1, with Hand Size from 6.40” to 8.75”.

Generally people with larger Hand Sizes used larger Glove Sizes. This was no surprise. Therefore, the Author concluded Glove Size and Hand Size could be numerically equated. Since clothing size names are meaningful to the general population, the Author selected seven size catagories to represent the Hand Size data, viz.: XS, S, M, M/L, L, XL, and 2XL.

A survey of available glove “Sizing Charts” was also performed. No universal agreement was found that correlated “Glove Size” with Hand Size. Glove Sizing Data was sourced below, each of which used the “palm to middle finger” definition of Hand Size (as opposed to "width of palm" definition)

Www.baistgloves.com
https://oberoncompany.com/resources/...-sizing-chart/
https://my.alfred.edu/environmental-...glove-size.cfm
https://www.sizechart.com/gloves/men...-us/index.html
Tutrtleskin Glove/Warwick Mills, Inc. (Grainger)

(The Oberon and Alfred sources appeared to use sizing much, much larger than the other three, and were therefore discarded. Both have similar large values, and it is not clear to me why. Perhaps they use a different target population, or account for palm width as well somehow. But I left them out because they were so far out of whack with the other three, which were very closely matched. Perhaps something to look into later.)

The remaining three sources were averaged, resulting in the below range of Hand Sizes for each Glove Size for further use in the Study.



Interestingly, the Hand Size range above (6.37 to 8.81) tracks closely with the study group range (6.40 to 8.75).

[RJ]

Analysis - Part 2

To date, the Author has found no industry standard metric to determine gun size.

Of course, some manufacturers use broadly descriptive terms to place guns in categories, but these are not associated with any specific gun dimension, other than generally. These include words like: Duty, Standard, Full Size, Compact, Subcompact, Microcompact, Pocket, and Single Stack, and for Revolvers, Snub Nosed, Small, Medium and Large Frame. Prospective purchasers are left wondering about fit, since there is no way to relate their hand size to these categories.

The goal of Part 2 was therefore to evaluate whether Gun Size could be objectively determined using a single measurement from the pistol itself.

The dimension selected for this was Grip Circumference.

Grip Circumference (GC) is defined as: the shortest distance around the entirety of the grip/stocks, including the trigger, measured along an axis from the rear of the grip at the “web of hand” position, to the vertical mid-point of the trigger face, and back.

GC accounts for stocks or grips, whether thick or thin. It starts at the "web of hand" location, and extends to the trigger face, so it also includes trigger reach (reflecting the typical hand location for initial trial fit of a pistol.)

A survey of guns owned by the study population was then conducted to obtain samples of GC. As of this post, participants provided data on 40 pistols. The data ranges from the Kahr PM9 at 5.79”, to a Walther P99 at 7.48”.

Since clothing size names are meaningful to the general population, the Author selected the same seven size catagories used for Hand Size to represent the Gun Size data: XS, S, M, M/L, L, XL, and 2XL.

To facilitate a numerical evaluation, it was postulated that the smallest gun surveyed represents XS, and the largest, 2XL. It was further postulated that the remaining Gun Sizes, for S, M, M/L, L, and XL, could be determined by numerically allocating the GC data, in the same proportions as Hand Lengths, linearly scaled.

The values of each “Gun Size” were thus calculated, providing a way to place guns into sizes, numerically. Finally, this data was put in a table of Gun Sizes and their associated Grip Circumference values:

[RJ]

Analysis - Part 2A - Gun Data - by GC

The Gun Sizing data table above was applied to the data (GC) captured in Part 2, with the following result:



This image represents the latest gun samples, sorted by Grip Circumference. At right, in purple color, is the calculated "Gun Size", based on the scaled GC data table computed above.

[RJ]

I realized I had hidden some of the columns in the above post, that were important to sizing information ("Modifications"). So in an attempt to fix that, I merged the cells into one hopefully more complete column, and reexported the table graphic.

I realize this is a bit of an eye test, but it's the only way I can think of to provide an overview of the data so far. Still working on the rest of this, Hand Table, Gun Table, etc.

There are some curious things emerging. By "Gun Size", my Ruger LCR is the biggest gun I own and my 1911 the smallest.

[Half Moon]

There are some curious things emerging. By "Gun Size", my Ruger LCR is the biggest gun I own and my 1911 the smallest.

I suspect the grip measurement needs refined somehow. Anecdata but my wife with small hands struggles with grip (really trigger reach to be fair) on K frame revolvers with uncovered backstraps; she loves the grip of her Beretta 92 either DA or SA (though she mostly shoots it SA); with L to XL hands I've always found the 92 grip clunky. Not sure how to quantify the nuances and you're working up at least a baseline but still nuances...

[RJ]

Hand Table

Reference the above, a “Gun Sizing” process is defined:

Step 1 Measure your “Hand Size” (see definition)
Enter the “Hand Table” to determine your “Gun Size”
Step 2 Enter the “Gun Table” and choose a gun that at or less LESS THAN your Gun Size

Example 1 You measure your hand size at 7.2”.
Using the Hand Table, you determine your Gun Size is Medium.
Selecting a gun that is Size Medium, Small, or Extra small will increase your likelihood of a good initial fit.

Example 2 You measure your hand size at 6.4”
Using the Hand Table, you determine your Gun Size is Small.
Selecting a gun that is Size Small, or Extra small will increase your likelihood of a good initial fit.

Example 3 You measure your hand size at 7.9”
Using the Hand Table, you determine your Gun Size is Large.
Selecting a gun that is Size Large or below will increase your likelihood of a good initial fit.

The Hand Table is below, in graphic image form. A downloadable PDF is also attached if a hard copy is desired.

[RJ]

I suspect the grip measurement needs refined somehow. Anecdata but my wife with small hands struggles with grip (really trigger reach to be fair) on K frame revolvers with uncovered backstraps; she loves the grip of her Beretta 92 either DA or SA (though she mostly shoots it SA); with L to XL hands I've always found the 92 grip clunky. Not sure how to quantify the nuances and you're working up at least a baseline but still nuances...

Yeah I am trying to ignore all that until I get to the end of this particular thread of reasoning...I mentioned in Part 2 maybe I would like to do a first pass, kinda pick something and see where it lands. The results are...interesting.

For example on their web site Glock classifies their firearms by what they call "Frame Size", as in Compact, Competition, Long Slide, Standard, and Subcompact. But according to the guns sampled so far, almost all the Glocks have identical or nearly identical Grip Circumference of around 172 mm. I'm not sure that is a coincidence.

I really would like to get more measurements on guns, in particular some of the smaller more popular ones like the G43, G43/48, S&W Shield, Shield OR and Springfield Hellcat.

I was gonna ask for a P320 but somehow that part of my post got…dropped.

rimshot

[RJ]

Going to take a break and ponder the Gun Table at this point. Although I have collected GC data on almost 50 samples, I'm not 100% sure how to set up a useful way to represent the data in Gun Sizes. The data on guns is posted above. Although a bit teeny, it renders legible for me on a screen as well as a tablet device (iPad) albeit with some stretching and shrinking.


I am considering two ways to create/use the Gun Table.

Method one is, having gotten your Gun Size from the Hand Table, you get your tape measure, take the gun you are considering buying, and get it's Grip Circumference. You enter a Gun Table with that value, and determine the gun's Size. If "your" Gun Size is at or bigger, you are good to go forward with that gun. If "your" Gun Size is smaller than the gun you are looking at, you may have issues with trigger reach.

Method two is first get your Gun Size, like before. But this time, you want to see what guns are in your "Size". So you'd enter the Gun Table with your size, and run your finger over all the entries that are at your size, or smaller. Any of these in your size, or smaller, could work for you, and you should avoid guns that are bigger than your size, since they may give you issues with trigger reach.

Method one would result in a Gun Table that was pretty easy; it would just have each Gun Size, by GC. It would look almost identical to the Hand Table, in fact, since both have 7 bands. Method two would generate a Gun Table what was kinda sorta a shopping list of guns, by Gun Size. This would require some estimation of where "generally" a gun or gun class would fit, within Gun Sizes. I mean, I could use the samples I got to represent the classes, but this gets into a gray area, since I don't have access to GC on "All" guns. Perhaps I could generate a guess as to "the top 50 guns sold last year" since that would cover the majority of what people are buying these days. Or maybe a hybrid, with Method 1 being in big font with the ranges, but below each Gun Size, would be "examples" of common guns in that Size to support Method 2, for comparisons sake.


Not sure which way to go, so I'm just going to pump the brakes on updates for a while to sort this out in my head.

Plus there is this nagging thought that representing Gun Size with a single value is not...optimal. I like the simplicity of GC, and that both HL and GC have 7 bands. It does make the math easy, for sure. But I don't quite know exactly what dimension on a gun I'd add to the GC to better approximate "fit" that would be both objective and easy for people to obtain, numerically. Hmmm.

[RJ]

Or maybe I need to rewicker "Gun" into "Grip". That would disconnect the physical size of the gun (e.g. Large, like a 1911) from the ability to reach the trigger (e.g. Small, like a 1911 with thin stocks and a short trigger pad.) From a word choice point of view, perhaps grip is closer to the mark, in terms of initial fit re: hand size to provide adequate trigger reach.

So:

Gun Size --> Grip Size
Gun Table --> Grip Table

Moar hmmm.