Optimal Barrel Length

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by victor, Mar 27, 2006.

  1. victor

    victor Well-Known Member

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    Optimal Barrel Length 21.75"

    Last night I read the "Houston Warehouse Chronicles" that was posted on this site some time ago.

    One bit of information that I found surprising was the recommendation that barrel lengths be exactly 21.75" long (I'm going by memory here, so let me clarify, that is what I remember the figure to be). Basicaly one of the gurus of that era stated that a barrel length of 21.75 has the best frequency for whipping bullets into the same hole each time.

    What I don't understand is that there was no mention of barrel diameter, or powder burn rate. It seems to me that both these factors have a lot to do with barrel harmonics.

    To put this picture in perspective, I imagine a fishing pole. A long skinny pole will whip back and forth quite a ways. But a short fat pole will not flex nearly as much. But add a thick wall to the long pole and the flex with be reduced.

    So my question is, how do they come up with 21.75" magic length as best for all applications.

    Thanks in advance,
    Vic
     
  2. IChaseCoues

    IChaseCoues Well-Known Member

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    I caught that too during the read!
    The length of 21.75" does not make scence to me either.
    Hopefully someone more enlightened can dumb it down for me.
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    I think someone is uneducated and full of crap. 21.? whatever may be perfect for some caliber(s) but no all. Bore diameter, case size, case dimension, case design and I am sure a whole lot more than that will determine what the best bbl length is. He probably reads "rifle shooter" of some other magazine that has no practical experiance...
     
  4. daveosok

    daveosok Guest

    You must first take into consideration the type and caliber they were shooting and what the subject matter covered.

    That length proved to be optimum barrel length for there particular circumstances.

    Dont take the 21 inches to mean that a 300 win mag shooting 200 grain pills will best be suited in a 21 inch barrel.

    The length of the barrel they choose will not meet the criteria for such cases as the 300 win mag, 7mm stw, Rem ultra series, Allen Mag series or any case capacity greater than say 70 grains of water.

    All of the above mentioned cases will need a lot more than 21 inches for opitmum barrel length versus case capacity.

    In a conversation with Dan Lilja I had a few years back he stated that for a 95% or better powder burn in a cartridge that had 70 or more grains of powder needed 34 inhces of barrel length. This was covering heavy bullets such as Berger's 180 grain VLD and now 175 SMK.
     
  5. Meister

    Meister Well-Known Member

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    Maybe best for standard calibers? I dunno the context but it sounds like a generality that holds no weight.
    The best truck is a ford....
    The best handgun is the 1911a1....
    The best beer is Old Frothingslosh...

    Maybe the guys spellcheck edited out "for me"

    Just my .02
     
  6. Bart B

    Bart B Well-Known Member

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    [ QUOTE ]
    To put this picture in perspective, I imagine a fishing pole. A long skinny pole will whip back and forth quite a ways. But a short fat pole will not flex nearly as much. But add a thick wall to the long pole and the flex with be reduced.

    [/ QUOTE ]I know there's a popular belief that stiff, rigid barrels shoot more accurate than those that whip or flex a bit more. Fact is, medium weight longer barrels have shot just as accurate as shorter, thicker and stiffer ones. Check out what the best accuracy attained in all centerfire rifle shooting disciplines is then find out what barrel contours were that did so well.

    I've heard of this particular barrel length before. Don't rmemeber what it was in, but that number now rings a bell.
    Seems it had something to do with the bullet from some "pefect" cartridge would make exactly 1.5 revolutions from a barrel that long.
     
  7. deerkiller

    deerkiller Well-Known Member

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    "Last night I read the "Houston Warehouse Chronicles" that was posted on this site some time ago."

    Read the story so you know the background & context.

    Deerkiller
     
  8. goodgrouper

    goodgrouper Well-Known Member

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    [ QUOTE ]
    I know there's a popular belief that stiff, rigid barrels shoot more accurate than those that whip or flex a bit more. Fact is, medium weight longer barrels have shot just as accurate as shorter, thicker and stiffer ones.

    [/ QUOTE ]

    Are these the barrels that you called "whippy" that were actually 7 or 8 contour barrels? Please, please, please, quit trying to portray the idea to the less learned here that true whippy barrels (like the ones used in hunting not bloody palma) are just as accurate as short, fat number 8 contours! <font color="red"> IF THEY WERE, EVERYONE IN BENCHREST WOULD BE USING THEM! </font> My God man, have you ever been to any REAL br match ever in your life?!

    I'll tell you what I saw at the last 100 yard NBRSA match I attended. 22 $3000 dollar rifles all wearing 21" super heavy barrels that measured between .9" and 1.1" diameter at the muzzle. WHY???

    The fishing pole analogy is correct whether it is fiber glass or stainless steel. Granted you can make a pencil barrel shoot accurately. No one is saying that you can't. But a short fat barrel IS stiffer and will therefore have more accuracy potential (especially if firing quick shot strings) plain and simple.

    I only get frustrated by people who try to confuse everyone on basic principles of firearms because they are never the ones who have to answer the confused emails that they cause day in and day out! Let me tell you, you have confused enough people to keep me busy till the cows come home!

    Uggh, I'm ok. Were is that damn Tylenol anyhow?
     
  9. goodgrouper

    goodgrouper Well-Known Member

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    Meichele is right. Every particular rifle and cartridge will have an optimal barrel length for accuracy and acceleration. Many factors go into it and thus far, only a few cartridges have been totally figured out. For instance, the 6ppc often shoots the best at 20-22" with the 65-70 grain bullets. It took many many years to figure out what the magical number would be with this cartridge. Much experimentation has been done with it because just about everyone who has been in competition the last 20 years has built at least one of these rifles.

    Some of the other popular calibers have not been continously tweeked with to this degree and the optimal barrel length is still being investigated.
     
  10. daveosok

    daveosok Guest

    [ QUOTE ]
    I know there's a popular belief that stiff, rigid barrels shoot more accurate than those that whip or flex a bit more.

    [/ QUOTE ]

    In benchrest where mutiple rounds must be fired in a certain time, heavy thick short barrels wont mirgrate due to thermal expansion.

    Thinner medium weight longer barrels simply cannot deal with the heat, number of firings, and thermal expansion as well as a barrel with more mass.

    50 rounds out of a medium weight longer barrel will simply not produce the same groups as 50 rounds out of a shorter heavier weight barrel. Thermal dynamics just wont allow it.

    On another point Bart, you havent had much positive or helpful input on just about every subject you've commented on. It always seems as if you've done it better, seen it done better, or can't be done better.

    Such as the remark about Darryl making the shot on an Elk at 2000 plus yards and not making it a one shot kill. Your assement of the military taking sighter shots is totaly absurd as any sniper knows the more shots you take the more you allow the enemy to focus in on where you are hence the one shot one kill pricinple.

    Darryl method is or should be exactly what all long range shooters should do as this isnt a human we are shooting at but an animal that cant equate at great distances who or where the shot is coming from allow mutiple sighter shots be taken to assure a proper shot.

    Simply going out and lining up on an animal 2000 plus yards away and letting one fly is a poor method. Unless you have something to proove like your the only one who can hit something at 2000 yards with one shot, taking sighters is the best way to ensure a good shot placement. Otherwise you are the one guessing and getting a lucky shot.
     
  11. Bart B

    Bart B Well-Known Member

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    [ QUOTE ]
    In benchrest where mutiple rounds must be fired in a certain time, heavy thick short barrels wont mirgrate due to thermal expansion.

    Thinner medium weight longer barrels simply cannot deal with the heat, number of firings, and thermal expansion as well as a barrel with more mass.

    50 rounds out of a medium weight longer barrel will simply not produce the same groups as 50 rounds out of a shorter heavier weight barrel. Thermal dynamics just wont allow it.

    Your assement of the military taking sighter shots is totaly absurd as any sniper knows the more shots you take the more you allow the enemy to focus in on where you are hence the one shot one kill pricinple.

    [/ QUOTE ]

    40 shots in 15 to 20 minutes will heat up a barrel quite a bit. When they all go into less than 2 inches at 600 yards, I don't think barrel heat caused any problems.

    And several 10-shot groups at 600 yards that measure .75 to 1.25 inch all fired back to back caused a lot of heat that didn't seem to effect accuracy. The batch of bullets used in these super-tiny 10-shot groups were spun in a collet at 30,000 rpm and those that didn't spin perfectly true caused the amp meter on the power cord to read higher. Only 1 in 10 spun good enough to use in the test.

    These were just tests to see if the rifle and ammo shot well. It wasn't in any type of competition. Barrels 26 inches long were straight tapered about 1.1 inch at the back end and .8 inch at the muzzle. .308 Win. cartridge in a Hart barrel fitted to a Win. 70 action conventionally bedded. Cases were full-length sized. I don't think shooting 50 shots would have caused any increase in barrel temperature than these did. Whatever thermal dynamics did wasn't enough to cause accuracy problems.

    The military folks taking 'sighting' shots I mentioned are those shooting 3-inch to 16-inch diameter bullets. Bullet diameter, target, equipment and range are the differences between these folks and that long-range elk-shooter. Techniques are identical.

    If you nay-sayers would get your head out of the 'benchrest' sand and learn that highpower match rifles shoot just as accurate with their longer, thinner barrels than the shorter, fatter ones used by the stool shooters, it would enlighten you. But I don't think that's gonna happen because it's too contrary to what you believe in. If one's sincerely interested in learning about this, I'll help you out. Otherwise.........well, never mind.
     
  12. BountyHunter

    BountyHunter Writers Guild

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    Bart

    If you have or know of any "across the course/Palma" 308 (or any gun for that fact) that can put 10 shots in .75" to 1.25" at 600 yards back to back you had better grab it and show up at every 600 yard BR match you can find. You will be a millionaire in a year.

    Reason is you have a WORLD RECORD rifle. Seeing as the world record at 600 yards is not even .750".

    Love these "I've got a gun that shoots ---, (which is a world record) but there is not one documented case of this "magical" gun ever showing up at a match and doing it anywere. Here at Quantico, I have seen more than one try and no one won the Kewpie doll yet.

    600 yard matches are everywhere now, show up and win the prize.

    PS When the military fires anything that is 3-16 inches, it is called "adjusting fire", not sighter shots.

    BH
     
  13. daveosok

    daveosok Guest

    There you go Bart. We seem to be forgetting the CONTEXT of the article. It wasnt about how to shoot extremely long range with 3 to 16 inch projecticles it was about small caliber benchrest rifles shooting extremely small groups.

    You cant compare plama, or military 3 to 16 inch projecticles with what they are proving.

    I bet that a heavy weight varmint barrel (custom) 30 inches long can withstand the thermal expansion rates more equally than a thinner light weight varmint barrel.

    When you have more mass the part of the barrel that is exposed to the air will less likely be affected by warping causing it to move in one direction or another, consequently a thinner barrel will have more thermal expansion due to its mass. In a timed event where you must placed 20 rounds downrange I'll bet that the heavier barrel wins hands down everytime.
     
  14. goodgrouper

    goodgrouper Well-Known Member

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    [ QUOTE ]
    Barrels 26 inches long were straight tapered about 1.1 inch at the back end and .8 inch at the muzzle.

    [/ QUOTE ]


    I would really like to know why you call this a non-target barrel when the rest of the world considers this a rather heavy target barrel. I don't believe the results you keep bringing up, however, this type of barrel would absolutely be better for longer shot strings than the barrels found on factory rifles which is what we HUNTERS use. And by the way, I have never shot a big game animal off my stool!



    [ QUOTE ]
    If you nay-sayers would get your head out of the 'benchrest' sand and learn that highpower match rifles shoot just as accurate with their longer, thinner barrels than the shorter, fatter ones used by the stool shooters, it would enlighten you.

    [/ QUOTE ]


    You keep saying that palma groups are smaller than benchrest groups. While I admittedly have never been to a palma match, I have a hard time believing that they are shooting better groups at 600 and 1000 yards than the "sand- headed" br crowd. If they are, then it isn't because their barrels are "skinny" as you call them. Your skinny palma barrel is fatter than several of my hunting barrels by a long ways.

    Perhaps you would like to enlighten us.
    I do happen to have the results for every BR match from the past two years in the western US and will glady post them and name their source if you would like to give us the results of palma from a reliable source (not just your word on it) so that it can be looked up by anyone, anywhere. My source will be NBRSA news which is the official newsletter of the benchrest circuit in the western US. And I'm sure other BR guys from the east would gladly give you the specs on the IBS league.

    OH, and another thing, you will notice the forum title. I visit this site because I apply long range principles to HUNTING. I don't care if the principles come from BR, Palma, tactical operations, or even cowboy action shooters. I will use them if it gets the job done. If I was just a straight paper puncher, I would be over at benchrest central forum only. So, before you accuse me or anyone else here of being tunnel visioned, maybe you should look at the different people here from all the shooting disciplines who are reading about MANY different ideas in relation to HUNTING which apparently, is something you don't do.