Optimum Barrel Length Data????
- Thread starter Nodak7mm
- Start date
I would like to see this as well but I don't know how it could be done. I know there are alot of ideas out there that claim to know the "correct" barrel length for a given caliber but I would doubt most of it.
I chased that rainbow some years ago trying to build a 6mm Rem on a Model Seven action with a 20 inch semi-heavy contour. My thoughts were making a short, stiff fast 6mm loaded with faster powder to compensate for the 20" tube and be able to drop deer while in the confines of my deer blind. My result was...they never knew what hit them.
Doug
Doug
There is a posting called the "The Secrets Of The Huston Warehouse" were a groupe of bench rest shooters had the use of a warehouse to shoot in they started at 30 inches and cut down a barrel till they would shoot the best http://www.angelfire.com/ma3/max357/houston.html a long read and very interesting.
Rod, a chart like that might be perfectly useful to its creator, but probably not to too many more people.
The first problem we'd run into is defining "optimum" with respect to barrel length. Is it the length that gives the highest MV? With almost any centerfire cartridge that would be over 40". Is it the length that gives a perfect sight radius for iron sights? Depends on whose eyes. Is it the length that gives the best accuracy scoped from a bench? What if you aren't a benchrest shooter? You see where I'm going...
Just about every decision we make when building a rifle involves compromises, balancing one factor against another - barrel length and contour are a very good example of that sort of balancing.
I prefer a relatively heavy barrel to absorb heat during a string of 22 to 25 shots, and I need a certain amount of barrel length to ensure enough MV for 1000 yard shooting, and to give me a useful sight radius - but I hate a muzzle-heavy rifle. I end up using a 28" barrel (except in .308 where I use 30") with a relatively heavy profile (MTU or Heavy Palma). If I were an F-Class shooter and didn't have to hold the rifle, I might go a bit heavier and a bit longer. If I were shooting offhand, I'd definitely go shorter and lighter.
When it comes to MV, longer barrels will always get you more MV (and lower SD, but that's another topic). However, they soon reach a point of impracticality and rigidity diminishes, so the MV gain is counterproductive. Of course, the longer it gets, the less MV per inch you gain, but it's a positive number until well past 40" for most centerfire cartridges.
Balancing all the factors and your needs will give you your optimal barrell length - and odds are it will have very little to do with the cartridge for which the barrel is chambered.
The first problem we'd run into is defining "optimum" with respect to barrel length. Is it the length that gives the highest MV? With almost any centerfire cartridge that would be over 40". Is it the length that gives a perfect sight radius for iron sights? Depends on whose eyes. Is it the length that gives the best accuracy scoped from a bench? What if you aren't a benchrest shooter? You see where I'm going...
Just about every decision we make when building a rifle involves compromises, balancing one factor against another - barrel length and contour are a very good example of that sort of balancing.
I prefer a relatively heavy barrel to absorb heat during a string of 22 to 25 shots, and I need a certain amount of barrel length to ensure enough MV for 1000 yard shooting, and to give me a useful sight radius - but I hate a muzzle-heavy rifle. I end up using a 28" barrel (except in .308 where I use 30") with a relatively heavy profile (MTU or Heavy Palma). If I were an F-Class shooter and didn't have to hold the rifle, I might go a bit heavier and a bit longer. If I were shooting offhand, I'd definitely go shorter and lighter.
When it comes to MV, longer barrels will always get you more MV (and lower SD, but that's another topic). However, they soon reach a point of impracticality and rigidity diminishes, so the MV gain is counterproductive. Of course, the longer it gets, the less MV per inch you gain, but it's a positive number until well past 40" for most centerfire cartridges.
Balancing all the factors and your needs will give you your optimal barrell length - and odds are it will have very little to do with the cartridge for which the barrel is chambered.
Nodak7mm
Team Lefse
Hmmm, so German what are you really trying to say? 
Maybe I should try to define which aspect of "Optimum" I am trying to obtain. I struggle at times trying to ask/communicate what I am thinking of. So I will do my best, by relating an example.
I read about test on the .308, during which the effeciency of the cartridge was compared against the velocity gain at a given barrel length. I dont recall the exact numbers, but there was a optimum point reached in velocity gains per a given barrel length.
However there is was a point where the gains "peaked". Each additional inch of barrel length added still yielded an increase in velocity, but not as "optimum/good" as it had when gains in velocity had peaked. The test would have looked something like this, consider all other varibles same, except bbl length:
18" = +6%
19" = +8%
20" = +11%
21" = +9%
22" = +7%
So in the above given theoretical test, the 20" barrel length acheived optimum gains.
Thats what I am looking for...
But German, you are so right in the other aspects that must be considered, specifically intended use. I am building in my brain, a hunting/tactical style rifle in a 6.5x47L and I am thinking right along 23" for an ideal length for my purposes in the barrel contour I intend to use..... Thanks, you always get me to step back and think, I like that and very much appreciate it....
Rod
Maybe I should try to define which aspect of "Optimum" I am trying to obtain. I struggle at times trying to ask/communicate what I am thinking of. So I will do my best, by relating an example.
I read about test on the .308, during which the effeciency of the cartridge was compared against the velocity gain at a given barrel length. I dont recall the exact numbers, but there was a optimum point reached in velocity gains per a given barrel length.
However there is was a point where the gains "peaked". Each additional inch of barrel length added still yielded an increase in velocity, but not as "optimum/good" as it had when gains in velocity had peaked. The test would have looked something like this, consider all other varibles same, except bbl length:
18" = +6%
19" = +8%
20" = +11%
21" = +9%
22" = +7%
So in the above given theoretical test, the 20" barrel length acheived optimum gains.
Thats what I am looking for...
But German, you are so right in the other aspects that must be considered, specifically intended use. I am building in my brain, a hunting/tactical style rifle in a 6.5x47L and I am thinking right along 23" for an ideal length for my purposes in the barrel contour I intend to use..... Thanks, you always get me to step back and think, I like that and very much appreciate it....
Rod
Rod,
interesting thread. I'm interested to know more about the 6.5x47 Lapua, you are building in your head? I'm building the same caliber rifle, with a 22" barrel and trued 700 ADL action. I went with Trueflight #3 contour (NZ made), as a compromise between stiff, but able to be carried on foot up mountains. As with German's post, I have made compromises, and also intend to upgrade the stock, as funds allow. I thought long and hard about a 20" tube, and using a 2 point mount suppressor, but decided it was easier to have it cut at a later date (if velocities were ok).
Sorry, not trying to hijack your original post, just interested
interesting thread. I'm interested to know more about the 6.5x47 Lapua, you are building in your head? I'm building the same caliber rifle, with a 22" barrel and trued 700 ADL action. I went with Trueflight #3 contour (NZ made), as a compromise between stiff, but able to be carried on foot up mountains. As with German's post, I have made compromises, and also intend to upgrade the stock, as funds allow. I thought long and hard about a 20" tube, and using a 2 point mount suppressor, but decided it was easier to have it cut at a later date (if velocities were ok).
Sorry, not trying to hijack your original post, just interested
Nodak7mm
Team Lefse
270Guy,
Not a problem and love to talk projects, so hijacking never remotely considered..
Just looking to use & replace a donor rem 700 VSSF safe-queen in 22/250 and utilize the factory HS stock and barrel profile. So the two possibles I have considered are another 22/250 in a fast twist to shoot 75/80 gr size or the 6.5x47 to shoot 123's. I am really leaning towards the 6.5 as it would be a great coyote/deer rifle also.
The barrel question comes up because a 26" or longer barrel is a pain to hunt with... So Im thinking a barrel length in the 20-24" range would be ideal, just would like to know where I stand for each inch of barrel length regarding velocities. That and the fact I may brake it too.
Thanks for bumping the thread.
Rod in Gawd Danged Soggy Butt with Fresh Snow on the Ground, Fargo ND
Not a problem and love to talk projects, so hijacking never remotely considered..
Just looking to use & replace a donor rem 700 VSSF safe-queen in 22/250 and utilize the factory HS stock and barrel profile. So the two possibles I have considered are another 22/250 in a fast twist to shoot 75/80 gr size or the 6.5x47 to shoot 123's. I am really leaning towards the 6.5 as it would be a great coyote/deer rifle also.
The barrel question comes up because a 26" or longer barrel is a pain to hunt with... So Im thinking a barrel length in the 20-24" range would be ideal, just would like to know where I stand for each inch of barrel length regarding velocities. That and the fact I may brake it too.
Thanks for bumping the thread.
Rod in Gawd Danged Soggy Butt with Fresh Snow on the Ground, Fargo ND
Nodak7mm said:
Rod.
I have found QuickLoad to be invaluable in exploring this question. Unfortunately, there can be such a wide variation in MV between two barrels of exactly the same specification from the same maker, that the absolute velocity estimates can be way off, but it is a very useful tool for comparing alternatives and trade-offs between barrels lengths, cartridges, projectiles and powders. I love to play with this stuff in my head and the program has saved my a fortune in expensive trial and error.
Nodak7mm
Team Lefse
it is a very useful tool for comparing alternatives and trade-offs between barrels lengths, cartridges, projectiles and powders. I love to play with this stuff in my head
Tony,
Ya know I have been wondering about if Quick Load can do that.. Thanks for the info..
Oh definitly, actual field results are always an unknown until your in the field. But it sure fun to try and figure out the unknowns with hypotheticals....
Rod
Tony,
Ya know I have been wondering about if Quick Load can do that.. Thanks for the info..
Oh definitly, actual field results are always an unknown until your in the field. But it sure fun to try and figure out the unknowns with hypotheticals....
Rod
Nodak7mm said:
It's like any other computer program in that it takes a while to even understand all of the things it can do, but, the more I work with it, the more useful things I find it can do. Most of us would agree that what is on the paper is all that matters, but this is definitely a tool that can help put better results on the paper.
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