Minimum barrel length to harness full potential of .357 round?

[Last Resort]

I noticed on another thread that many feel that a snubnose 357 is essentially wasting powder. Due to the shortened barrel length, much of the increased power of the 357 round is lost. For this reason many say a .38 snub is just as effective. I was wondering what you guys think would be the minimum barrel length to harness the power of a .357 round. Would a 4 inch barrel be more preferable? For somebody who is interested in conceal carrying a wheelgun that can actually harness the potential of a .357 round, what is a good make of revolver?

[knight0334]

With magnums - the longer the better.. The 357mag was designed with a 6" barrel in mind. The "spec" for the 357mag calls for a 158gr slug at 1450fps from a 6" barrel.

I personally was launching 125gr slugs from my 8" Colt Python at 1950fps, and 158gr slugs at 1625fps.

With any shorter barrel, with any other cartridge, you will have substantially lesser velocities. But a "magnum" will generally perform better than a nonmagnum in the same short barrels. Yes, you do not use the cartridge to its true potential - but the additional boost is often desired. However, you will generally suffer from excessive blast from the unburnt powder.

[Last Resort]

Thanks for the info. If I understand your post correctly.....a 6" barrel (or longer) would be optimal for the 357 round. Anything shorter then 6" is suboptimal. If going under 6" then a magnum would be preferable. Perhaps a 4" magnum (SP101) is reasonable.

[knight0334]

Yep.. 6" is optimal. Longer is better yet..

A 4" barrel is a fair trade off for carrying and making use of the cartridge's potential.

Here is a site with a inch-by-inch test of barrels with cartridges. just clicky on your favorite cartridge for the results.

http://www.ballisticsbytheinch.com/results.html

[WVBob]

You said Minimum. As said before, 4 in. is the minimum but you do not get near full power. 6 in. is as short as you want to go. If you need something for CC get a .38SPL and shoot +P in it.

[max384]

Although you do obviously lose a lot of the potential with the shorter barrel shooting the .357 magnum, you also lose a lot of the potential when using a .38 SPL in a short barrel. If you choose a very short barrel (as is often the case in a carry weapon) you will sacrifice performance no matter what round is used.


WARNING: NERDY SCIENCE STUFF:
Another aspect to keep in mind is Newton's laws. According to Newton's third law, for every action there is an equal and opposite reaction. What this means to the shooter is if one is shooting different rounds from the same gun, the round that produces the largest recoil will also have the highest energy upon contact with the intended target. This ignores any variables such as wind resistance differences due to different shaped bullets, etc. - which are minimized at relatively short distances anyhow. If two different guns are compared against each other, this does not work because the two may have different masses - the heavier of which will absorb more of the impact. They could also have different grips which could cushion better than the next... Anyhow, going back to the recoil point. When I shoot .357 magnums, .38 SPL+P, and .38 SPL out of my S&W .357 mag with 2" barrel, there is a noticable difference in recoil between all three. The largest jump is from the .38 SPL+P to the .357 mags. This tells me that there is more energy downrange from the .357s as compared with the .38 SPLs (high pressure rounds or not).

Obviously, you will lose performance shooting .357 magnums out of a snub-nosed revolver... but you are still better off firing the powerful magnums than the .38 specials.

[pred]

For every inch less the 6" you will lose approx. 50 FPS.
I would not worry, Folks have been using short barrel guns for many decades and the FBI used 3" and most PDs at some time or another used 2" Smith Chiefs specials or Colt Detective specials all in 38 special.
I only carry 357 occasionally, Mostly 38 special wad cutters.
And when camping when I really want some potential, 44 mag out of a 3" barrel.
Peter

[PA Rifleman]

I noticed on another thread that many feel that a snubnose 357 is essentially wasting powder. Due to the shortened barrel length, much of the increased power of the 357 round is lost....

The trick is matching barrel length with powder burn rate. Let's illustrate the extreme examples first. As you pointed out, if the barrel's too short, the bullet will depart at the muzzle while it's still developing pressure. Thus, it will waste powder and therefore energy.

The opposite extreme is too long a barrel. In this case, the barrel pressure has diminished down to the point where friction is actually slowing the bullet down.

Take a moment to examine the pressure graph, below.

Here's an example of a pressure curve from a rifle:

(Click on the image to see the document source)

Think of it in two seamless sections: the initial ramp upward to the peak, and the slope down from the peak all the way to the instant of bullet exit.

The first section is the initial pressure buildup immediately following ignition. During this phase, there is very little (if any) bullet movement. It's all static pressure.

The peak is brennschluss, or burn-out. This is when the last of the powder should be burned if there's enough time (barrel length).

The slope following the peak is bullet movement, which increases internal volume. This causes the pressure to decrease and the internal temperature to decrease slightly. As the bullet continues further down the barrel, the pressure continues to decline, exerting less unit pressure (force) on the bullet. If the barrel were long enough, eventually the force on the bullet would drop down equal to the friction between the bullet and the barrel, and acceleration would stop. Any additional barrel length would cause velocity to decrease.

The ideal point for bullet exit is just after the bullet reaches peak acceleration. If you're into math, look up Boyle's General Law for the explanation of this pressure curve. The ideal point in the pressure graph is probably where the area under the curve ceases to gain any appreciable area when viewed progressively from left to right. This chapter of math is integral calculus. Matching this point to the barrel length is the holy grail of reloaders and ballistic technicians.

Interesting animated gif showing this in Wiki:



In our case, the interior temperature should be increasing as internal volume decreases.

Summary:

Choose a barrel length that works for you, then try several different type of ammunition for your gun. The round that performs best is the right choice. Reloading will allow the user to match the performance curve even closer to the barrel length, and gain better performance.

Barrel length by itself generally increases accuracy as it's shortened, since the remaining barrel length (stub, if you will) becomes progressively more rigid with a higher natural resonant frequency. In actual practice the opposite is usually observed because humans get added to the equation. Our bodies prefer longer barrels for optical convenience (read: sight radius) and added stability from increased longitudinal mass.

...what is a good make of revolver?

Not touching that question, the math & science aspects are a lot easier.

Hope this helps.

[Dextrimental]

Excellent post Pa Rifleman. I'd give you rep but the button is currently broken.


Brad

[RickD]

PA Rifleman, that was superb! Wow.

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