Hand Length to Gun Fit: A Case Study: RFI for Data on Hand Size (Part 1)

[the Schwartz]

@RJ I’m not sure this will help but I hope it does.

These are the two guns for example: PM9 versus P365.

Grip size is similar, gun size is similar but the trigger wall and reset is very different.

I’m not sure how this can be accounted for and calculated.

Attachment 107540

Attachment 107541

I might be offering an overly complicated answer (positive that has ever happened before ) as to how this measurement can be obtained but, what about using the measurement tool bar in a PDF?

All that is necessary to do so is to take a picture, much as you have done above and then convert it to a PDF so that the measurement toolbar can be used to obtain a linear value. Of course it would also be necessary to include a measurement scale standard so that the correct correction to scale can be made. The measurement scale standard must also be placed in the same focal plane as the measurement to eliminate/minimize error.

I use this very same technique in order to determine the average expansion diameter of recovered bullets that have been fired in water tests. The process is similar. After conversion of the image to a PDF, I use the PDF measurement toolbar to obtain the area of the test bullet's expansion face and then solve for the diameter accordingly after adjusting for scale. It is a process that is much, much more accurate than getting out a set of dial calipers and measuring individual maximum and minimum expansion values to obtain an average diameter.

[RJ]

Are you considering SA/DA pistols too?

Absolutely!

[RJ]

Thanks all for the input so far, it is much appreciated.

I've been pondering what to do about the sizing data, in that it appears the forum's population is a bit larger than the subjects in 1472D. So I decided to refactor the centile numbers assuming the lowest reported value was at the 5% centile, and the largest at 95%. This will allow some future variation in sizing, and more relevantly reflect matching gun size to hand size for this group.

To that end, the table now looks like this:



To answer a question, to date out of the 20 respondents, 19 have been male, so I'll focus on the male group for the moment.

[JTQ]

Male
6.5"
Men's size small glove

[BN]

I'm either double oh nine or M-19. If I'm M-19 am I a Glock or a S&W? Thread drift.

This is all pretty interesting.

Some thoughts. The original 1911 had a flat mainspring housing and the 1911A1 has a round one. Some of the replaceable backstraps on various handguns fill in on the top of the grip and others don't.

[JTQ]

Some thoughts. The original 1911 had a flat mainspring housing and the 1911A1 has a round one. Some of the replaceable backstraps on various handguns fill in on the top of the grip and others don't.

Another consideration, the original 1911 had a long trigger, while the 1911A1 had a short trigger.

[Yung]

M
7 1/8"
Medium

[RJ]

All data through above post is now collected, thanks very much.

It came to me last night, in terms of population across p-f, male vs. female, it doesn't matter. In fact, as far a fitting a handgun goes, the key point of all this is to be able to get one single measurement on a human (any human) and then get some kind of sizing guide to pick a handgun. That's it.

I don't know why this didn't occur to me sooner. I was pondering the shoe size analogy. Like when you were a kid, you go into the shoe store, and put your foot on the little measuring plate, boom, this is your shoe size you use to pick from. I know there are men's and women's shoes, and I am stretching the point, but you get my drift.

For purposes of this case study, what I am heading towards is a simple Hand Length to Grip Circumference relationship. I'm not sure exactly what form that will take, or how many buckets those measurements will divide into. We typically have Glove sizes of S, M, L, XL, etc. so it seems natural to have HL the same. It's easy to fit guns into that same paradigm, but after noodling on all the possible gun sizes over in the Part 2 table (about to post that soon) it seems to me we need to break down gun size a bit finer, hence the shoe size analogy.

Anyway, will post the current Hand Length table shortly, with the complete M/F data set, with male/female removed. It's also auto-adjusting for 5%/95% centiles, so the values of where subjects fall will move around a little.

[RJ]

Posting current p-f population Part 1 Hand Length (HL) dataset, refactored to include all subjects, no gender.


Part 1 HL Data range compared to 1472D "Ground Troops":



Part 1 HL tabular data, with recomputed centiles, reflecting largest HL = 95% and smallest HL = 5% of population:

[Clusterfrack]

M
7.25”
Glove size: S/M*

Comments:
I use tight fitting gloves for good dexterity, and Mechanix small stretches to fit me like a glove.

I stretch my firing hand around the grip by adding significant pressure at the web. This makes my hand effectively larger.

IME, trigger reach is less important than how the hands fit the grip. As @Surf posted on his excellent video on trigger press, where the finger hits the trigger isn’t that important as long as you can make a right angle at the 2nd joint to help pulling it straight.