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I've been a pistol owner for a few years now and I'd like to hear where you guys find information (articles?) on choosing ammo. I think I've maybe only seen a couple of articles in the last 5 years or so in American Rifleman or someplace like that discussing the topic. I also carry a short barrelled 9mm (Kahr PM9) and am interested in learning about selection. I carry Hornady Critical Defense and Winchester PDX mainly because that's what I can find at Academy (and they are both heavily advertised in gun mags). I did read this exhaustive study on ballistic performance at some point with the article linked below. Warning: this gets into a lot of physics. I think it makes the case that Energy is not as important as Momentum when looking at stopping power or wound area. I'd appreciate some opinions on the article or links to other things that could aid in our common understanding of ammo selection.

http://www.angelfire.com/art/enchanter/terminal.html

I built a spreadsheet at some point in the past comparing the Momentum of everything from .32ACP to .44Mag but only based on whatever data I could round up for various rounds. I did this initially to try to understand the difference in stopping power between calibers more than to select a particular ammo offering in one caliber. At the time I was trying to examine the much debated differences between 9mm, .357 Sig and .40S&W. Obviously there are tons of choices out there in each caliber so what I found was that people who entrenched themselves about one caliber over another were not examining all the options (+P, different weights, different speeds, etc). Depending on the particular ammo brand and offering I found that you could find one in each caliber that was quite a bit more effective than another. The other variable that comes into play is barrel length. In any case it is very much an apples and oranges comparison from one person to the next since so many things are not the same.

Regardless of that I went on to develop a further study between some common brands in a few of the calibers (9, 40, 45). I can confirm that Corbon makes one of the top 9mm defensive rounds based on the momentum calculations.

I don't know if I can post an excel file on here or not. If so, and if anybody is interested (and could tell me how to do it) I'd be happy to. Or I'll email it if someone wants to PM me.

I would love to see your study and conclusions.

Topbuilder wrote:I would love to see your study and conclusions.

I didn't do the study. I linked to the study. I just did some basic math to calculate the momentum of various ammo. That part's not that hard, but I captured it in excel. It looks like the author of the study has a chart that captures some of the same stuff I did too. I don't remember seeing that when I first read the study years ago, so possibly he has updated it since I read it the first time.

Unfortunately doing the math for the momentum doesn't really give you anything other than momentum. While Momentum might be a better estimator of one shot stop than Energy, it doesn't take into account expansion of hollow point ammuniton and the different variables that play into that (whether the ammo is travelling at the right speed for max expansion, out of the right barrel length to produce the right speed, etc).

xb12s wrote:

Topbuilder wrote:I would love to see your study and conclusions.

I didn't do the study. I linked to the study. I just did some basic math to calculate the momentum of various ammo. That part's not that hard, but I captured it in excel. It looks like the author of the study has a chart that captures some of the same stuff I did too. I don't remember seeing that when I first read the study years ago, so possibly he has updated it since I read it the first time.

Unfortunately doing the math for the momentum doesn't really give you anything other than momentum. While Momentum might be a better estimator of one shot stop than Energy, it doesn't take into account expansion of hollow point ammuniton and the different variables that play into that (whether the ammo is travelling at the right speed for max expansion, out of the right barrel length to produce the right speed, etc).

, Honestly I don’t worry too much about what is written on SD ammo.

I shoot stuff through my carry gun to make sure it will load and shoot, exstract 100% no FTF, FTE.. then I mix a batch of ballistic gel and shoot it. If that SD ammo in THAT gun expands as designed... I have a match.

Velocity, and background, tech reports form magazines are all well and good.. but the only thing that matters to me is My gun, ammo I bought, and how it shoots / reacts.

Here's a website that has the Marshall and Sanow one shot stop figures in an interactive form.
http://www.handloads.com/misc/stoppingpower.asp" onclick="window.open(this.href);return false; Select your caliber and your bullet weight or, look at all bullet weights and see the one shot stop probabilities of various calibers. These figures are from actual police and CHL shootings not from lab tests.

edit: Let me say this, their definition of a one shot stop was if the Bad Guy stopped their aggression within five seconds of being shot that was a one shot stop. Double taps and multiple shots weren't included. The psychological stop was included "OMG I'm shot gotta fall down!" if the BG stopped within 5 seconds it was a OSS.

Slight drift, but another consideration, in addition to the ballistics, penetration , etc. is whether the round is optimum for your gun.

I had been using 147 gr. rounds in the P226 Navy very satisfactorily, but started having problems when I got a P7M8. Come to find out, through the HK forum site, that the P7M8 was designed for 124 gr bullets, and the 147's didn't work reliably. That was news to me; I didn't recall seeing anything like that in the gun manual. I came right home and separated the 125 gr from the 147 gr., made sure they are kept separate, and had no more problem. I have no idea if other makes/models have such limitations or issues.