Velocity loss due to barrel length

[stubshaft]

I have always been enamored with short barrel guns and have acquired over my career a number of "snubbies" in a wide variety of calibers. I even went as far as to cut down a Contender in 44 magnum to 4" just for the heck of it.

That being said I am intimately acquainted with the velocity loss due to the lack of barrel length. I found this link which has a variety of calibers and their respective velocity loss and/or gain based on barrel length.

http://redirect.viglink.com/?key=71f.../calibers.html

[Wilderness]

I recall an article in American Rifleman from a long time ago on the subject of velocity loss as a revolver barrel, I think a .44 Mag, was shortened.

Velocity dropped off as expected until it stabilised at about 1050 fps. Even with the barrel stub screwed out, velocity was still 1050 fps.

Then the penny dropped. When bullet velocity fell below the speed of sound, the chronograph was actually triggering on the sound wave ahead of the bullet.

I have had a similar experience with a .30-30 with bronze colored powder coated bullets that did not trigger the chronograph. Their actual velocity was around 1800 fps, but the Oehler was telling me about 1050 fps. I presumed that it too was picking up the sound wave in the absence of a meaningful bullet shadow.

So be careful about data that is around the speed of sound.

[GregLaROCHE]

I wonder if as the barrel gets shorter, if the powder should get faster. As I remember 44 mag rifles like slower powder than handguns.

[racepres]

I wonder if as the barrel gets shorter, if the powder should get faster. As I remember 44 mag rifles like slower powder than handguns.

I guess I thought this was gospel... been told since the '70's!!!!

[HumptyDumpty]

Matching powder burn rate and charge to barrel length has been one of the my favorite benefits of reloading, and it is something I never even thought of initially.

[charlie b]

I have always been enamored with short barrel guns and have acquired over my career a number of "snubbies" in a wide variety of calibers. I even went as far as to cut down a Contender in 44 magnum to 4" just for the heck of it.

That being said I am intimately acquainted with the velocity loss due to the lack of barrel length. I found this link which has a variety of calibers and their respective velocity loss and/or gain based on barrel length.

http://redirect.viglink.com/?key=71f.../calibers.html

Thanks for that link. Showed data on what I suspected for short barrel pistols.

[44MAG#1]

While interesting I don't let barrel length concern me enough to cause me to stop using them.
BBTI has been around a long time.
I like short barrels.

[georgerkahn]

stubshaft -- thanks for posting this! A (long) while back I fell in love with a 2"-barreled .44 Mag revolver, with -- as much as I viewed it as eye-candy, plus! -- I did not execute purchase as I reckoned its short barrel would not allow much velocity to be achieved. At lease compared to a long barrel. I reckoned, too, there'd me more smoke and noise...
Anyhoos -- I enjoyed actually seeing the velocity change data.
Thanks again!
geo

[44MAG#1]

Of course I am the oddball and a few other things that could be thought of. The way I look at short barrels is this. I know that a longer barreled 44 Mag will give more velocity than a short barreled 44 Mag.
I know a long barreled 41 Mag is more powerful than a short barreled 41 Mag.
I know a short barreled 357 Mag is less powerful than a long barreled 357 Mag
But I ask myself the question would I rather be armed with a short barreled 44 Mag than a short barreled 357 Mag when that 3990.5 pound Black Bear looks at me with lust while holding a fork in one paw and a steak knife in the other.
I'll take the 2.75 inch M69 rather than a 2.75 inch 357 Mag.
I know all I'll make are bad shots so I would rather make a bad shot with a 44 Mag than a 357 Mag.
The shot placement guys may want to shoot me down on this.

[Paul105]

Way to many variables. Different guns, different environmental conditions, different components, how you curl your tongue, etc.
.
All that said, here are some actual chronograph results that might be of interest. First group with Labradar at the muzzle. Second group at 5 long paces with Competition Electronics.


Buffalo Bore, 305 LBT LFN HC rated 1,325 fps
Underwood, 305 LFNGC Plated (HiTech?) rated 1,325 fps
LabRadar muzzle velocity at 33 deg F
.
S&W M69 2.75" ===> BB 1,195 fps ===> Under 1,147fps
S&W M69 4.25" ===> BB 1,276 fps ===> Under 1,248 fps
Ruger SRH 7.5" ===> BB 1,395 fps ===> Under 1,315 fps


.
325gr WLNGC Beartooth Bullets
22.0gr H110
Fed 155 M
New Top Brass
Five long paces from muzzle, Temp 45 – 70 deg F

7 ½” Ruger SRH …. 1,279 fps … ES 33 fps … 70 Deg F
6” S&W M629 ……. 1,269 fps … ES 16 fps … 70 Deg F
4 ¼” S&W M69 …… 1,182 fps …ES 13 fps … 45 Deg F
4” S&W M329 …….. 1,085 fps … ES 26 fps … 60 Deg F (CCI 350, diff pwdr lot)
2 ¾” S&W M69 …… 1,104 fps … ES 9 fps … 68 Def G
.
FWIW,
Paul

[Outpost75]

With revolvers you need to consider that barrel-cylinder gap is as important as barrel length. In .38 Special revolvers firing normal police service loads the expected Delta-V is a 10 fps difference for each 0.001" change from Mean Assembly Tolerance. It.is entirely normal for a 2-inch gun at min. assembly tolerance of 0.003" pass and 0.004" hold to produce higher velocity than a 4" gun at Customer Service Maximum of 0.008" max. and 0.009" hold. The difference is greater with +P and magnum ammo.

[MarkP]

I like short barreled rifles for hunting. Hunted elk in the mountains of Colo with a 26" bbl rifle. Never again, 20" Rem M Seven KS is so much handier to carry on a sling while hunting in the mountains. Also when I was younger I like long barreled revolvers and thought snubbed were silly to own.... now I like snubbing.

[beemer]

These are my personal revolvers, all three are Ruger Six Series. Load is 6 grains of Unique with a Lee 158 grain and a gas check. This the average for 6 shots.

2 3/4 " 924 fps
4" 948 fps
6" 985 fps

I like short barreled pistols, especially snubbies. Everything is a trade off. You just have to figure out what you are willing to trade off.

Dave

[44MAG#1]

I hesitate to post this as I will be in the crosshairs of the experts on chronographing.
But I'll take my lumps.
Here is the SAME LOAD chronoed on the SAME morning BACK to BACK.
44 Mag loads. Smith and Wesson M69 2.75 inch 1112 fps. Smith and Wesson M629 4 inch 1247 fps. Ruger SBH 3.75 inch 1272 fps.
All used the H&G 503 bullet with the narrow front band, Alliant 2400, Federal 150 primers and Starline cases.

[dtknowles]

To me the accuracy difference is more important than the velocity difference. Most people shoot longer barreled revolvers more accurately than Snubbies. I rarely am pushing velocities to the max anyway. I don't think I own a revolver with a barrel shorter than 3", I own revolvers that have cylinders half that long. Controllability and sight radius are important to me.

Tim

[Harter66]

See Why ballistians get grey in the Speer manuals . It has a table of 20+ different makes models and barrels from , if memory serves, 1-1/2 to 8-3/4" 357 mags in the lab . I want to say 100 rounds of a single lab tested load in each one . There were a couple of examples of shorter barrels being faster than than longer barrels . I had a load in a 16" carbine 45 Colts that went 1260 and out of a 7.5" RBH it was only 600 fps most loads like the preferred 1050 load did about 1240 in the rifle .

[shooting on a shoestring]

Barrel length is just one factor in the velocity of a load fired from a revolver.

As Outpost75 mentions the barrel/cylinder gap makes as much, or almost as much difference as barrel length. But there’s also chamber diameter and throat diameter. They can make a difference too. Another factor is how much room the shell casing has to move backward before it hits the recoil shield. That has the same effect on case capacity, but in the opposite direction, as an auto-loader having boolit set back from hitting the feed ramp. And don’t discount the difference in force on the primer strike from gun to gun.

Barrel length is the easiest to see. It’s literally hanging out the front of the gun. It’s very intuitive to think shorter barrel means less velocity. And that’s true it does, usually. But…..it’s not the only dancer in the overall performance. So it is quite possible for tolerance stacking to lead to a shorter barrel gun shooting the same load faster than a longer gun. Unusual, yes. But it happens. But sometimes a long barreled gun with loose dimensions will shoot slower than expected.

Personally I don’t choose a barrel length for velocity. I choose a barrel length for usefulness. That use might be a short one for carry. Or it might be a long one for weight to slow down the wiggly front sight. Or an in between one for a nicer balance or better look.

[44MAG#1]

Barrel length is just one factor in the velocity of a load fired from a revolver.

As Outpost75 mentions the barrel/cylinder gap makes as much, or almost as much difference as barrel length. But there’s also chamber diameter and throat diameter. They can make a difference too. Another factor is how much room the shell casing has to move backward before it hits the recoil shield. That has the same effect on case capacity, but in the opposite direction, as an auto-loader having boolit set back from hitting the feed ramp. And don’t discount the difference in force on the primer strike from gun to gun.

Barrel length is the easiest to see. It’s literally hanging out the front of the gun. It’s very intuitive to think shorter barrel means less velocity. And that’s true it does, usually. But…..it’s not the only dancer in the overall performance. So it is quite possible for tolerance stacking to lead to a shorter barrel gun shooting the same load faster than a longer gun. Unusual, yes. But it happens. But sometimes a long barreled gun with loose dimensions will shoot slower than expected.

Personally I don’t choose a barrel length for velocity. I choose a barrel length for usefulness. That use might be a short one for carry. Or it might be a long one for weight to slow down the wiggly front sight. Or an in between one for a nicer balance or better look.

Could one also say temperature makes a difference? Could doing the testing on different days make a difference? Could we say not using the same lot of the same ammo could make a difference? So it could be said that generally a longer barrel produces more velocity but not necessarily each and everytime?

[Larry Gibson]

Could one also say temperature makes a difference? Could doing the testing on different days make a difference? Could we say not using the same lot of the same ammo could make a difference? So it could be said that generally a longer barrel produces more velocity but not necessarily each and everytime?

Most definitely they make a difference. Same with what Outpost75 said. Let us not also consider the quantity of shots in the test and test to test variation of the same load in the same test firearm. Many other variables to consider besides barrels length.

I went through the short barrel phase with handguns and rifles. Now days I prefer barrel length in both. Note my avatar; that's a 23 lb M60 MG. I liked carrying it because it and its cartridge worked when it came time to shoot. It was not short or easy to carry but that's not what mattered. Same with hunting rifles. I prefer them with 24 - 26" barrels. I've never really found "easy to carry" to trump what is important when it comes time to shoot. With handguns I find those with 4 - 6 1/2" barrels to be easy enough to pack in a belt holster and 7 1/2" barreled revolvers easy enough with shoulder or chest holsters. Again, easy to carry, handy and easy to get out of a vehicle do not resonate with me. In the last war where we did a lot of carrying, CQB [again, I never found barrel length to be a hindrance there if one was trained in proper weaposcraft] and getting in and out of vehicles they kept saying "hey Top, why the 'A2, let me issue you an M4. I'd say "no thanks, but I'll take an M14"....that just got me a deer in the headlight look......What's important, the only thing that's important, is how well you can handle and shoot [meaning hitting the target with the first shots].

[Paul105]

I'm in my mid 70s and really like my short barreled gun.