No chrony here, but I shoot a 24" barreled Rossi.
My only long gun 357.

RP

 

This should help you to gain insight on velocity bbl length: BBTI - Ballistics by the Inch :: Home

Jack

 

thanks for that chart. IT did not show 24" barrel velocities,but it doesnt look encouraging. IF this is the case other than a longer sight radius what is the benefit of a 24" barrel over the 20 or 18.5? Its more weight and balance is more forward.

 

thanks for that chart. IT did not show 24" barrel velocities,but it doesnt look encouraging. IF this is the case other than a longer sight radius what is the benefit of a 24" barrel over the 20 or 18.5? Its more weight and balance is more forward.

Yes,in lever action silhouette the extra length helps in offhand balance with weight forward and I don't know about velocity difference between 20" and 24",but the difference between pistol length and 24" is dramatic.

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That’s interesting to hear it slows down with longer barrel.

 

Well, it demonstrates that with factory loads but if one handloads, one can choose a slower burning powder for longer bbl's to maintain velocity. The objective is to use a powder that ends it's burn the moment the bullet exits the muzzle. Then the bullet doesn't slow down.

Jack

 

I just bought a 24” Winchester Legacy.357 Saturday. If it stops raining I will compare velocity with my 18.5” Marlin. I’ll reply with results.

Dan

 

I can tell you all kinds of if’s, and’s or but’s but it boils down to what @JACKTW said.

 

My favorite load at the moment is a 180 gr wfn from MB co. called the pugnose over 11.4 grs of 2400.
Pretty decent group at a100 yds.
Thought I had pic., but can't find it at the moment.

RP

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JACKTW beat me to my point. Optimization comes with hand loading for the given rifle. Most ammunition in the pistol caliber rifles is designed for use in handguns. Very few are designed with rifles in mind.

 

I lean on Lil Gun for my 357 loads. It seems to offer very low pressures and very high velocitys. Perhaps that would take advantage of the long 24" barrel. The bullets I tried are the Hornady XTPs in 158gr and 180gr as well as Remington jacketed soft nose which my 1894C loves best. But I would like to see someones FPS figures with the barrels along with factory or handloads just to see for myself whats happening.

 

Stopped raining for about half hour so I did some velocity testing with my two .357 rifles.

First load was 158gr MagTech JSP with 14.9 grains AA#9, CCI Standard primers. All loads used Starline brass.

Marlin 1894 18.5”
Average 1795 fps
ES 24*
STD 10
*two pairs of duplicates

Winchester 24”
Average 1822 fps
ES 47
STD 19

2nd Load 12.0 TCM 158 gr Hornady XTP CCI Standard Primers.

Marlin 1894 18.5”

Average 1505 fps
ES 75
STD 30

Winchester 94 24”

Average 1501 fps
ES 66
STD 25

Dan

 

I get 1750 FPS from my 16.5" 1894 using H110 and 158 grain XTP. I can tell you that this load is very accurate in the Marlin and works well on white tails. I need to test it in my 18.5" Ruger M77/357. I will get to that this summer along with trying some Lil'gun and some 180 grain XTPs. I doubt that I will move away from the H110/158 XTP load because I have a lead bullet load that shoots to the same point of impact. This is very handy for practice. .357 rifles are economical in terms of powder and shot. This is a very good thing now days.

 

In a pistol caliber carbine, powder NEVER burns the length of the barrel. That is a physical and ballistic impossibility. Study the pressure curve of typical piezo-electric data and you'll see that even the slowest pistol/shotgun powders reach peak pressure (when all of the propellant is consumed) when the bullet has traveled 1" or less. It's true, the slower powder's gas keeps expanding longer, but never burns to anywhere near the muzzle. Common misconception keeps this falsehood alive.

The faster pistol/shotgun powders are completely consumed before the bullet even leaves the cartridge case. I encourage you all to study in detail internal ballistics, especially max pressure curves, time of propellant burn, and barrel time chamber-to-muzzle. Even in the giant Weatherby magnum cases, all the powder is consumed by the time the bullet has traveled 4 inches from the case mouth. It causes bore erosion and throat burnout.

So while slower powders provide better velocity in pistol caliber carbines, powder burn to the muzzle simply isn't possible. The peak of the pressure curve tells the story. It's why there's no throat burn out in .357 and .44 mag carbine barrels. There's no powder burning in the throat area to erode the barrel steel.

 

Funny, I knew someone would take my "slower powder burn" analogy... to make a point, literal. 🤣

I wanted to make it back to elaborate more on the subject but I'm entirely too busy lately.

Thanks Rob.

Jack

 

Here's a generalized pressure curve of smokeless powder. See the vertical line and the pressure peak? That's when the powder supply runs out, as it's all been combusted. No more pressure can be produced. Slower powders can move the peak a little to the right, broadening it, but we're talking millionths of a second burn time.

 

YEs the dynamics are very well illustrated, thanks. But I thought as long as there was still pressure while the slug is in the barrel it keeps it maintaining speed buildup. Of course the drag issue comes into play as well. Thank you all for responding .

 

There has to be a certain amount of pressure to overcome the weight of the projectile and the friction. . Once the pressure falls below that level, acceleration ceases and deceleration starts happening.

All smokeless powder has approximately the same energy output per unit of weight. The slower powders reach peak pressure over increased time, so more weight can be loaded safely in the cartridge case. More weight means more energy output.

But there's a limit in practical ballistics using nitrocellulose powder. 4400 ft/sec is the fastest a bullet can be driven. That is the practical limit in conventional firearms technology.

 

Well I decided to chronograph a factory load of American Eagle 158gr SJSP out of my 18.5" Marlin 1894c barrel and my friends 24" Marlin cowboy. Seems all your technical writeups arent behaving as you think.
18.5" 1894C --1750sp
24" 1894cb --1809fps.

Looks like the positive pressure is still accelerating that far.

 

One must always remember rifle barrels are not always the same. The real test on velocity and barrel length is start with a long barrel and record velocities as the barrel is cut back. To me velocity is not near as important as accuracy. No barrel cuts in my shop.
Have a great day.
Jim

 

Yep, accuracy is key and believe me Ive tested many loads from factory to my own handloads. Heres what happened yesterday at the indoor 25 yard range . My friend just bought his used 1894cb 24" 357 rifle last week. He knows nothing about guns so I went with him to help him along. We never touched the iron sights.I took the very first shot with Am Eagle ammo and hit dead center of the 2 inch red dot. Next shot went thru the same hole. The third shot widened the hole a little at 25 yards. Federal American Eagle has shown great accuracy with my 1894c as well. And almost 60fps more from 18.5 to 24" is on the positive (good side) to me. So Im happy.

 

There will be little difference between 357 mag velocity in a 18.5 vs a 20 inch barrel.

357 mag powders burn quickly reaching a pressure peak while the bullet is still in the barrel, in contrast to bottle neck magnum calibers which are slower burning and continue building pressure until the bullet is much nearer the end of the barrel.

As has been mentioned above, this means that beyond a certain length (it works out to about 14-18 inches for 22 LR) no significant velocity is gained by lengthening the barrel. Actually for such calibers long barrels, can even slow the projectile beyond what it would have been for a shorter barrel. Realize that friction also continues as the bullet traverses the bore.

This from Ballistics by the Inch Ballistics by the Inch

Click to enlarge.

The proper way to do this is to take a long rifle barrel and cut it off, an inch at a time, recrowning the barrel after each cut. Then velocity measurements are gathered at each length and a table is constructed.

I suspect that the tables above were constructed from firing different rifles with different barrel lengths, rather than a single rifle and cutting the barrel.

In any event, note that the fasted measured velocities were at 16" barrel length. Although there was some variation in velocity with lengths longer than 16", the changes in velocity thereafter were small.

The value of a chart like this one, is not the absolute numbers, but the trend. Velocity will increase with barrel length up to a certain length, and afterward will decrease. This maximum is different for different calibers, different bullet weights, different powder choices, and different loads. No doubt there are other factors as well.

Beyond that, increasing barrel length serves only to contribute to esthetics, sight radius, balance, and weight.

 

ok, well my chronograph shows me what I needed to know.

 

A 158 grain bullet going 60 ft/sec faster (1750 to 1809) gains about 60 or 70 foot/pounds of energy and flies .10" flatter midrange trajectory at 50 yards. Who cares? Accuracy and on target precision beat velocity any day.

How do you think 55,000,000 buffalo died? Bullets and round balls traveling at 1150-1200 ft/sec killed them all.

 

^^^^ and most of those lead slugs and balls came from long barreled rifles, but with black powder ^^^^

 

Trust me when I say I can get a 357 mag over 2k with 140 grain pills. I’ve gotten the same bullet in a 357 max at just over 3k in 24” single shots. If you get over 1800 FPS with a 158 g pill in a 24” rifle what more do you need accept a 180 g doing almost the same.
If you want the most out of your 357 you are hand cuffing yourself passing up mag primers and W-296. 2400 is the only other powder even close and is better in extreme cold in my experience. Yes my experiments were over recommended loads but 1800+FPS 180 g is attainable with recommended powder loads in 20 and 24” barrels. Mag primers.

 

2400, IMR4227 and AA#9 were designed for pistol sized rifle cartridges.

They do work in pistol cartridges, but are meant for 18" to 20" barrels. They do pick up just a little in 24" barrels.

You will have to test your handloads for the best performance. IME, one of those will give the best speed and accuracy. This is also true with Magnum pistol loads.