This is going to be a big reply, but somebody on another forum asked the exact same question, and seeing as I have a copy of Quickload, I figured I could calculate the ballistics of various cartridges for different barrel lengths. Quickload CANNOT simulate the cylinder gap, so you can expect the real results to be WORSE than the calculations. With a 2" 357 snubby, you are still throwing most of the baby out with the bath water. In a SHTF situation, it's better than nothing, but the ONLY way I would put my life on the line with ballistics this anemic is if I WERE dead. The nice thing about this exercise is that it's all apples to apples, so data from 7 different manuals doesn't cloud the issue.
Okay, I got the results worked out. Briefly, I went to the Hornady handloading manual, and picked out the +P or maximum normal loads listed, and stuffed those variables into Quickload. FWIW, Quickload is a pretty sophisticated program, and its purpose is to allow you to experiment without actually blowing yourself up, which makes it worth a paltry $150 to old mad scientists who got a lot of hospital work left. :yikes:
So, once I got the data loaded and ran the cartridge for the longest barrel length that was to be tested to verify that it was within safe calculated limits, I just re-ran the data for shorter and shorter barrel lengths, since barrel length is a separate variable in this program. I tried to use Power Pistol whenever I could to remove some more variability from this exercise.
The net result is that the comparisons are all apples to apples across the board, so this data is uniformly calculated and presented.
Here's the data, with a few comments to go with. There are definitely some cartridge and barrel length combinations that you want to avoid like the plague!
The 9mm Luger round (9x19 mm) is a pretty straightforward round, and WYSIWYG. It's a small diameter bullet, but the velocity stays good, and the ft-lbs of energy don't precipitously drop off like the next cartridge.
The 38 Special is a nasty surprise in anything shorter than a 5" barrel, which is probably why all the original guns had 5" or 6" barrels!! With a 2" snubby giving you only 600 FPS velocity and 100 ft-lbs of energy, you're getting concealability and giving up nearly all of the stopping power.
The 45 ACP has good solid performance in a 6" to 3" barrel, and there's not much to worry about across the board. There's some additional info on the last graph, and shows that a big, slow bullet is better than what these numbers show..
The 357 mag is known for plenty of punch, and generally it delivers the goods. However, as you can see, the stopping power trails off very rapidly with 3" and 2" barrels, with the 2" barrel only giving you 200 ft-lbs of stopping power. That is NOT a reassuring amount of punch when your life is on the line!
The 40 S&W round is also pretty straightforward, and with a 5, 4, or 3" barrel you stay above 300 ft-lbs of punch.
The last chart is the Taylor Knock-Out Factor for the above rounds, because the formula for calculating ft-lbs is an invitation to many snake oil salesman posing as ammunition companies to pull the wool over your eyes and get rich.
Without going into the difference between weight and mass, the formula for ft-lbs is 1/2 the mass of the bullet times the SQUARE of the velocity. The diameter of the bullet isn't even considered!!
The Taylor Knock Out Factor was named after an African big game hunter AND poacher, who had learned that a 220 Swift bullet with a gazillion ft-pounds of energy at 4000 fps wouldn't do diddly squat against a rhino or elephant. The bullet HAD to be close to 1/2" diameter, weigh close to an ounce, and had to going Mach 2 or better.
This explains why the TKO for the 45 ACP is head and shoulders above the other cartridges. In addition, the top end of this chart is around a TKO of 17-18,which is what you have with a full power 44 magnum load using a 240 grain bullet going 1800 FPS out of an 8" barrel. Curiously enough, a 5" barrel 50GI has the same TKO score, with a 50 cal 300 grain bullet going 900 FPS.
Seeing as I mentioned the 500 Smith snubby in another post, I thought I would add that to the list. Previously I had mentioned that with a 2" barrel 500 (which they DO sell!!) you are losing most of your velocity and hitting power. I was mostly right, and the 2" barrel ft-lbs number is appalling.
In a regular Smith 500 with an 8" barrel, with a 350 grain 50 caliber slug you get 1850 FPS
and 2782 ft-lbs, which gives you a fighting chance to stay alive with a brown bear. The Taylor Knock-Out factor is in the mid 40's, which is getting up into African hunting rifle territory. With a 2" barrel, however, the velocity goes from 1892 to 852, so you only have 45% of your velocity left. The ft-lbs goes from 2782 to 564, so with a 2" snubnose Smith 500 you give up 81% of your stopping power, and 564 ft-lbs won't do diddly squat to a half ton of bear!! S&W should be ashamed of themselves for putting a $1K+ booby trap like that on the market.