caliber/barrel length chart

[hiram]

Is there a chart that shows the optimum barrel length according to caliber and burning rate of powders?

[MT Gianni]

I would love to see what the optimum cartridge is in each caliber for a contender, 10" 12" 14" & 16".

[Blacksmith]

21 3/4"

To quote from Secrets of the Houston Warehouse


But no bit of information was, Virgil believes, more valuable than a little advice Jim Gilmore passed along. Jim said a barrel MUST be 21 3/4” long for optimum accuracy. That precise length, he stated, sets up a vibration pattern that duplicates well from shot to shot. Virgil faithfully followed that advice on his guns.

Anyone who strictly observes the 21 3/4" doctrine will screw off a failing barrel of that length and run a new one under it. Rechambering and rethreading, in order to achieve more pristine lands just forward of the throat, shortens the barrel. Shorten the barrel, spoil the magic length.

Through the years, the Houston Warehouse shooters were able to rate the relative accuracy of the various benchrest calibers — .22, 6mm and .30. In the perfect conditions of the warehouse, the .22’s outshot them all, followed closely by the 6mm’s. The .308 calibers were a not-too-distant third. The most accurate .30 caliber ever to find its way into the warehouse also belonged to Virgil. The rifle, built around a Shilen DGA action with McMillan barrel, shot consistently within a few thousandths of .100". The barrel length? You guessed it: 21 3/4".

Here is the link to the full story.
http://www.angelfire.com/ma3/max357/houston.html

Buy the way .30 caliber Mann Accuracy Barrels are 21 3/4" long. Used for testing ammunition lot consistancy for the government.

[Chicken Thief]

Has to do with boolit weight/shape/material also so it will get mighty big, fast!

[Artful]

Is there a chart that shows the optimum barrel length according to caliber and burning rate of powders?

Not really but you can use Quickload software
http://www.neconos.com/details3.htm
it will let you play with variables to find best match to what you want.

review
http://www.6mmbr.com/quickload.html

[danski26]

First you would have to define "optimum" Hiram. A projectile will continue to accelerate inside the barrel until the friction imposed on the projectile by the barrel overcomes the pressure of the expaning gases behind it. In other words, in order to start losing velocity a barrel needs to be VERY long. Like 40+ inches for the 308 Win.

As the Chicked Thief mentioned, this is also dependant on the projectile, powder, barrel, action type and atmospheric conditions. Some of the software can "estimate" a pressure curve and its effect "velocity" on a projectile, but this is just an estimate.

So to answer your question, no there is no chart that gives you THE optimum barrel length according to caliber and burning rate of powders.

[hiram]

By optimum, I was getting at a barrel/caliber where all the powder would be efficiently used in the barrel. i.e., I have read somewhere that the optimum barrel length for a 22 rimfire is 16". I was just trying to get a handle on when you have a firearm built, how long should a barrel be when the gunsmith asks the question.

I met a guy once who said he saw 28" 45-70's shoot as well as 30-32" 45-70's. When I had mine built, I ordered a 28" barrel and have not been disappointed.

[Blacksmith]

I corected my #3 post and added source information.

Here are links to some barrel length vs velocity testing by Bullberry Barrel Works:

17 HMR Velocity Tests

http://www.bullberry.com/HMRdata.html

204 Ruger Velocity Tests

http://www.bullberry.com/204Rugerdata.html

[Artful]

In the VOL. 9, NO. 4 issue of GUNS & AMMO magazine, Bob Milek wrote an article titled:
BARREL LENGTH VS VELOCITY, where he took a number of barrels and guns and cut down the barrels in one inch increments, measuring the velocity loss at each step of the process for a number of centerfires as well as the 22LRs. It's a very interesting article. Here are the velocities recorded for the 22LR starting at 14 inches and going down to 4 inches.

22LR
14" = 1,105 fps.
13" = 1,106
12" = 1,110
11" = 1,089
10" = 1,114
..9" = 1,077
..8" = 1,063
..7" = 1,057
..6" = 1,024
..5" = ..959
..4" = ..927 fps.
- observe the 22LR 10" barrel's actual velocity vs what computer would predict...

Here another link about 22LR http://ammoguide.com/myag/articles/tloc54/Length_Velocity_Pressure.pdf

Software will allow you to predict this but you still have actuality that gets in the way
http://www.loadammo.com/Topics/October05.htm

223
http://www.accuratereloading.com/223sb.html
http://sadefensejournal.com/wp/?p=1093
http://www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf
http://img228.imageshack.us/img228/7243/223plot8py.gif

6mmBR
http://bulletin.accurateshooter.com/2011/12/barrel-length-and-velocity-barrel-cut-down-tests/

300 blk vs 6.8
http://www.300blktalk.com/forum/viewtopic.php?f=128&t=78987
http://img692.imageshack.us/img692/3653/screenshot20120210at814.png

308 WCF/7.62x51 NATO
http://www.chuckhawks.com/rifle_barrel.htm

http://i42.photobucket.com/albums/e303/taylorwso/308barrelvelocities.gif



What she did was cut a rifle barrel from 26 to 16 inches, to see the difference every 2 inches. Here is the results, it will give you an ideal what you are looking for. She used Remington factory 180s.

The first colume is Barrel length, velocity & energy at the muzzle, then velocity and energy(ft/lbs) at 300 yards.

26 2826 fps 3,192 2240 2,005
24 2722 fps 2,961 2149 1,846
22 2713 fps 2,942 2141 1,832
20 2677 fps 2,864 2109 1,778
18 2654 fps 2,815 2089 1,744
16 2552 fps 2,603 2000 1,599

* notice same barrel just cut back and 18" vs 20" only lost 23 fps

and



The 2001 Edition of the Shooter's Bible states, in the introduction to the Centerfire Rifle Ballistics section, "Barrel length affects velocity, and at various rates depending on the load. As a rule, figure 50 fps per inch of barrel, plus or minus, if your barrel is longer or shorter than 22 inches." But they do not say what category of load to which this 50 fps average pertains.

Jack O'Connor wrote in The Rifle Book that, "The barrel shorter than standard has a velocity loss which averages about 25 foot-seconds for every inch cut off the barrel. Likewise, there is a velocity gain with a longer barrel." He went on to illustrate this using a .30-06 rifle shooting 180 grain bullets as an example, so his estimate was obviously for rifles in that general performance class.

Other authorities have tried to take into account the different velocity ranges within which modern cartridges operate. The Remington Catalog 2003 includes a "Centerfire Rifle Velocity Vs. Barrel Length" table that shows the following velocity changes for barrels shorter or longer than the test barrel length:

MV 2000-2500 fps, the approximate change in MV per 1" change in barrel length is 10 fps.
MV 2500-3000 fps, the approximate change in MV per 1" change in barrel length is 20 fps.
MV 3000-3500 fps, the approximate change in MV per 1" change in barrel length is 30 fps.
MV 3500-4000 fps, the approximate change in MV per 1" change in barrel length is 40 fps.

The 45th Edition of the Lyman Reloading Handbook also has a table showing Center Fire Rifle Velocity Vs. Barrel Length. Their figures apply to barrels between 20 and 26 inches in length and agree with the Remington figures. The Lyman table shows the following approximate velocity changes:

For rifles with muzzle velocities in the 1000-2000 fps range, the change in velocity for each 1" change in barrel length is 5 fps.
For rifles with muzzle velocities in the 2001-2500 fps range, the change in velocity for each 1" change in barrel length is 10 fps.
For rifles with muzzle velocities in the 2501-3000 fps range, the change in velocity for each 1" change in barrel length is 20 fps.
For rifles with muzzle velocities in the 3001-3500 fps range, the change in velocity for each 1" change in barrel length is 30 fps.
For rifles with muzzle velocities in the 3501-4000 fps range, the change in velocity for each 1" change in barrel length is 40 fps.

The 43rd edition of the Lyman reloading Handbook gave some concrete examples of velocity loss for specific calibers and loads. The Lyman technicians chronographed some high velocity cartridges in rifles with barrels ranging in length from 26" down to 22" with the following results:

The average loss for the .243 Win./100 grain bullet was 29 fps per inch.
The average loss for the .264 Win. Mag./140 grain bullet was 32 fps per inch.
The average loss for the .300 H&H Mag./220 grain bullet was 25 fps per inch.

For standard high intensity cartridges in the same test, the Lyman technicians chronographed the cartridges in barrel lengths ranging in length from 24" down to 20" with the following results:

The average loss for the .270 Win./130 grain bullet was 37 fps per inch.
The average loss for the .270 Win./150 grain bullet was 32 fps per inch.
The average loss for the .300 Sav./180 grain bullet was 17 fps per inch.
The average loss for the .30-06/180 grain bullet was 15 fps per inch.
The average loss for the .35 Rem./200 grain bullet was 11 fps per inch.

After a bunch of disclaimers, the Lyman people concluded, "The rule of thumb is that high speed, high pressure cartridges shed more speed in short barrels than do the low speed, large bore types." It's funny, but that is what I had suspected all along!


7.62x54R Mosin-Nagant
another cut back experiment
http://honors.usf.edu/documents/Thesis/U82488180.pdf

338/375 Weatherby Magnum
http://www.riflebarrels.com/articles/bullets_ballastics/long_barrel_velocity.htm

9x19mm Luger Carbine
http://www.saysuncle.com/2006/08/30/9mm_performance_with_barrel_length/
http://img.photobucket.com/albums/v355/rowdyfisk/Misc/9mm.gif

357 Magnum
http://www.ballisticsbytheinch.com/357mag.html
http://i15.photobucket.com/albums/a351/Kirtmc/357speedvsbblength.jpg

45 ACP Handgun
http://www.w0ipl.net/Vel-45ACP.htm

.45-70
http://thefiringline.com/forums/showthread.php?t=212367
http://img514.imageshack.us/img514/9457/4570sammimaxload2oy.gif

50 BMG
http://www.riflebarrels.com/articles/50calibre/lengths_velocity_50_bmg.htm
http://www.anzioironworks.com/barrel_length_vs_fps.htm

12 gauge
http://forum.saiga-12.com/index.php?/topic/19103-barrel-length-vs-velocity/

A great resource Links
http://www.ballisticsbytheinch.com/
http://www.6mmbr.com/barrelfaq.html#24640

and loved this little blurb
http://www.guns.com/the-myth-of-barrel-length-and-velocity-loss-5571.html#comments


Well it goes back to yet another myth, also long ago proven wrong. This is the myth that smokeless powder continues to burn the full length of the barrel.

Homer Powley, who was perhaps the best ballistician of his day, found that all smokeless powder gets burned up right in front of the cartridge and even the most powerful magnum rounds burn their powder at the closest three inches to the cartridge. The reason you look down your barrel and see so much unburned powder is because the wrong powder has been matched to that cartridge. A properly matched round will only have a small amount of powder left to look at.

Takeaway


So what about those nice super long barreled rifles meant for super long distances? Well unless you’re a military sniper who intends on waiting in a position for three-days for a shot, you’re better off going portable and getting yourself a nice short barreled rifle. It will do the same job—and you can carry it all day!

A friend of mine who has forgotten more about ballistics and reloading than I will probably ever know long ago showed me his results from similar tests with identical guns of different barrel lengths. His results bore out the truth that a long barrel length is not needed in a rifle other than to look the part of a “sniper” rifle.

[DCM]

Well I have seen this beat to death before, have read the whole Houston warehouse story have also read the OBT paper http://www.the-long-family.com/ and Dan Newberrys OCW stuff.

After letting the information overload settle in for a long while and sorting through the facts I do know to work I have to go with Artful on this.

The most useful loading tool I have purchased Of late is Quickloads. I have used it extensively to develop loads to my liking. Weather it be a low flash pistol load or a Dangerous game rifle load.

It is very accurate when you feed it as much info as possible.

Now for what that has to do with the O.P. question.
If one plays with it you will quickly see that some combinations are obviously far better than others.
It will help you develop optimal loads for your barrel length.
It will help you to determine optimal barrel length for the caliber and components you think you want to use or it may convince you to use something different.

Once you play with it enough you will understand there is no optimal barrel length for a center-fire caliber as their are too many other variables at work.

Twist, chamber cut, throat, bullet design, powder, cases, primers, rifling type, rifling depth, seating depth etc etc ......
Quickloads doesn't compensate for all of these variables, but you can get really close without firing a shot. It will give a % burn and %ballistic efficiency for your setup

Sorry for sounding like a QL salesman and the long post.

So what caliber/bullet/powder/chamber/rifling etc. are you thinking of?

[Artful]

DCM sorry didn't mean to give "information overload", just trying to show pretty much what you stated.

[Artful]

Hiram, did this help answer your question or did I confuse you?

[hiram]

Artful-

I'll have to study the charts longer. Thanks for the time you put in on that.

What I was trying to get at is i.e., If I had a 308 win and used 43gr of WW748 powder, how long would the barrel have to be to have 100% of the powder burn in the barrel, and not any of it get blown out? Seems that unburnt powder blowing out of the barrel is a waste.

[Artful]

Hiram,
the burning of gunpowder in a rifle is almost never completely 100%.
This is due to the conditions needed to sustain the burn and once you have set off the powder and the condtions change inside the barrel you will get some kernels that will be pushed into a condition where they won't ignite.

Here's a link where this was dicussed before and I found interesting...
http://m14forum.com/ammunition/100745-does-barrel-length-effect-chamber-pressure.html


By the most basic reasoning, most people have always assumed that the max pressure is at the point where the bullet jumps from the case and is forced in to the lands (the very front end of the chamber area). And like other's pointed out, today's powders have been designed to try to sustain peak pressures for as long as possible. But there is still only one point in time when the pressure is at it's absolute maximum.

That point in time is effected by one more factor that people don't usually recognize, the time it takes for the powder's combustion gases to heat and expand. Those heated gases are what create the pressure that pushes the bullet along the bore and it takes a slight amount of time for the gases to reach their highest temperature which then create the max pressure. Putting all that together means that the peak pressure is just slightly forward of the lands. In the cases I sight below, the peak pressure is at about 3.5" from the bolt face using IMR 3031 powder and approx. 3.0" from the bolt face using Varget. Obviously Varget burns faster but in both cases the point of max pressure is about an inch or so in to the lands. Notice that the times marked at the bottom of the graphs are in milliseconds (so 0.4 represents 0.0004 seconds).

The graphs below are pressure/time curves for a 155gr .308 bullet using two different powders (IMR 3031 and Varget). Both curves represent the same max pressure. Notice that the peak of the first curve is slightly wider than the one in the second (compare the width of the curve at the MAP-25% level). That means that the pressure stays high for a longer time with IMR 3031 and that results in higher velocities (the muzzle velocity is a product of the length of time that there is high pressure behind the bullet as it moves down the bore). Notice also that I had to use more powder with Varget to get the same pressure for this comparison (41.1gr of IMR 3031 vs. 43.2gr of Varget). Just for information, the estimated muzzle velocities were 2678 FPS for IMR 3031 and 2604 FPS for Varget.

IMR-3031

http://media10.dropshots.com/photos/493614/20110711/164326.jpg

Varget

http://media11.dropshots.com/photos/493614/20110711/164504.jpg

But to answer the original question, no, for all intents and purposes, barrel length has no real effect on chamber pressure. The pressure is a product of the powder charge weight and the bullet weight more than any other combination of factors. Other things have slight effects (bullet crimp, seating depth, neck diameter, etc.) but those are the two main things that directly effect the pressure. Using the above load data, the pressure was estimated to be a little over 47500 PSI in a Winchester case using a 22" barrel. When I changed the barrel length to 16.25" the pressure stayed the same.

The pressure in the barrel will decrease as the bullet moves along the barrel increasing the size of the pressure vessel that contains all the gases that were created by the burning of the powder. Assuming you get 2800 fps - the bullet will move 2.8 feet in 1/1000 of a second so that would mean 32 inch barrel would give it time to get thru the end of the above graph's

[DCM]

What I was trying to get at is i.e., If I had a 308 win and used 43gr of WW748 powder, how long would the barrel have to be to have 100% of the powder burn in the barrel, and not any of it get blown out? Seems that unburnt powder blowing out of the barrel is a waste.

Ok ASSuming you are using a 168BTHP Sierra Matchking @ 2.800 OAL, 56.00g case capacity and all else goes according to Hoyle and QL 33.2" minimum :shock:.

Change the bullet, case capacity,OAL etc. and things will be different.

But in the real world I would have to agree with Artful yet again.

The low flash pistol load I developed with the help of QL showed the powder as being 100% burnt about 1.4" before the bullet exited the muzzle.
When we video taped the night firing the was a small flame with small sparks in it that exited the muzzle.
This load was FAR better than any of the factory ammo tested thus far but it still had a flame(hot gases?) and sparks(powder burning??).

I have not come up with a way to confirm my suspicions yet so it it obviously just my opinion at this point.