Decrease throat erosion with longer barrels?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by TracySes23, Jun 8, 2013.

  1. TracySes23

    TracySes23 Well-Known Member

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    Recently I ordered a new Savage LRVP in 22-250 from their custom shop. A few weeks after I ordered it, I began to think, I might have preferred to make a change or two.

    The first change I wanted, was a change from the LRPV Synthetic stock to the Palma BR Beavertail stock, which I managed to get changed, but was too late for any other change.
    The second change I considered was a change in barrel length from 26 inches to 28”, 29” or maybe even a 30” barrel. After pondering over this for a while I opted to keep the 26-inch barrel for one reason only. The possibility of barrel whip & loss of accuracy.

    Now I wish I’d have posted this before I ordered my new rifle. I’m not even sure my concern about barrel whip was valid.

    I think the biggest reason most people want a longer barrel is to obtain a higher velocity. However, this wasn’t my reason. I’ve always been very conscious barrel erosion and have always waited several minutes or more between shots while feeling the barrel to guesstimate when to shoot again.

    I have spent hours searching for information hoping to discover someone who has considered & tried the following.

    My logic suggested to me, I could use a barrel 2-4 inches longer (28-30”) and load to the same velocity as a 24-26 inch barrel with a lighter powder charge and possibly reduce barrel erosion. Maybe this concept would also work with an Ackley improved cartridge.
    As mentioned before, I do not want to sacrifice accuracy from barrel whip for barrel life.

    My rifle will have the LRPV fluted barrel (added cooling & lighter weight) & the Palma BR beavertail stock with vents, which I want for added cooling & the way it sits a bit better on the front rest.

    Any input from experienced long-range shooters would be appreciated.
    If a new rifle or a new barrel is in the future for me, I want to be sure I’ve considered everything possible.

    I hope this all makes sense, because it seems a bit disorganized to me.

    Spencer
     
  2. azsugarbear

    azsugarbear Well-Known Member

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    To my knowledge, barrel length has little or nothing to do with erosion in the throat area. Charge weight (hot loads) and rate of fire seem to be the two variables that impact erosion the most.
     

  3. idaho elk hunter

    idaho elk hunter Well-Known Member

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    I have always been a advocate of longer barrels to a point. Barrel whip is very much a factor.lightbulb.. If a Standard Mag (7mm-300mag) Barrel is around the 28 in range and the SUPER MAGS( ultra, 30-378 etc) mags are around 31 inches in length, One would be able to load up to max loads and pressures and back off 2 grains to their SWEET SPOT. The sweet spot should be above the velocity and power of a standard 22 to 24 in barrel and far superior killing potential and accuracy. I might add that I have done several long barrel mag jobs on Weatherby cartridges with both carbon wrapped technologies out today. Both gave me more barrel whip and lesser accuracy than a fluted standard barrel.
     
  4. TracySes23

    TracySes23 Well-Known Member

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    That was my point. I considered you could get the same velocity with a longer barrel using less powder. Hence get less barrel erosion than a shorter barrel with the same velocity.

    I haven't read about anyone trying this before.

    Spencer
     
  5. TracySes23

    TracySes23 Well-Known Member

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    Since I'm not a hunter other than backyard squirrels or rabbits eating my garden. I'm not too concerned about getting maximum velocity.

    However, maybe I can get what's considered maximum velocity from a 26 inch barrel out of a 28-30 inch barrel with a lighter power charge. Less powder, less erosion.

    Savage sells at least three of their guns with a 30 inch barrel and one with a 29 inch barrel. These are all Target Series rifles, which I assume all are capable of competition at 1000 yards.

    If 3-4 inches of additional barrel length over a 26 inch barrel will give me a signifiant gain in velocity, then I could easily load back to a lower velocity with less powder.

    Remember, I'm only looking for less barrel erosion.

    I'm just a paper puncher with only a maximum of 500 yards available.

    I have also looked for some charts that would give me velocity gains for each inch of barrel length for the same charge weight. So far, no luck.

    I'd just like to run across someone who's considered this approach to less barrel erosion.

    Apparently I was correct in thinking my original post was a bit confusing. The questions I've been asked so far have helped me to explain things (hopefully) a little better.
    I've never read about anyone considering a longer barrel for anything other than a higher velocity.

    If this still seems confusing, please tell me. I won't get good answers if I don't ask questions that make sense.

    Spencer
     
  6. xjsdvr

    xjsdvr New Member

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    1) use a longer bbl/rate of twist to get more bullet stability

    2) reduce throat erosion by keeping your pressures down.........
     
  7. TracySes23

    TracySes23 Well-Known Member

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    1 in 9" twist is plenty fast enough for the bullets Ill be shooting in 22 caliber.

    Less powder is exactly what I was suggesting when going to a longer barrel.

    Spence
     
  8. Michael Eichele

    Michael Eichele Well-Known Member

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    IMHO, longer barrels only help you gain velocity by giving you more burn area volume to burn more powder (more of a slower burning powder) thus increasing your velocity potential. All else being equal, I feel adding barrel length only adds friction that slows bullets down. Imagine a 100 foot long barrel chambered in 308 win. Would the bullet even exit the barrel?

    If you start with a 30" barrel, work up a load that is optimum for your barrel/bullet/powder combo, then cut 2" off, you will loose some velocity. Adding more of the same powder may bring your velocity up but the powder/barrel length/etc...is no longer optimal. Using a faster powder solves this problem. You get your velocity back and optimize your load/barrel relationship. This is just an illustration of my point. All this said, shortening your barrel and using faster powders may be the way to increase throat life as adding barrel length increases the time the bullet is in the barrel adding to the duration of heat and flame exposure to the throat. Honestly, I think you're barking up the wrong tree.
     
  9. TracySes23

    TracySes23 Well-Known Member

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    Michael,

    I understand your logic and if it's true, then if I shorten a barrel to say 20 inches then I should have longer barrel life. Am I applying your logic correctly?

    When looking at specifications at the Savage website, I see barrel lengths of 26, 28, 29 & 30 inches for varmint and target grade rifles. Using your reasoning should I assume all lengths above 26 inches will erode barrels faster as the lengths increase?
    Now I'm potentially confused in an area where I wasn't before.:)
    I do appreciate your input.

    Fortunately I'm not in a hurry to get this settled in my mind. I just like to venture into areas of extreme thoughts at times.

    If you have anymore thoughts, chime in.

    Spencer
     
  10. azsugarbear

    azsugarbear Well-Known Member

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    Most barrel erosion occurs in two areas of the barrel: the throat and the muzzle. The throat gets the brunt of the abuse through heat and chemical. The muzzles tends to wear and becomes less round and more "fish eye" in shape. As a general rule, bullets will gain about 25 fps for every inch added. But this is only true for barrels in the 20' to 26" range. After that, it becomes a game of diminishing returns. It can actually become a detriment and slow the bullet down if the barrel is too long. Dan Lilja wrote a pretty interesting article on the subject a while back:

    Lilja Precision Rifle Barrels - Articles: Barrel Lenghts and Velocities in the 338/378 Weatherby Magnum

    Both the 308 and the 30-06 get great barrel life and throat wear. You begin to see some shortening of barrel life in the 300 Win Mag. The 300 Ultra Mag shows even more. A max load for a 180 gr. bullet in a 308 is approx. 48 gr. of Win 760 @ 2600 fps. A max load for a 180 gr. bullet in a 30-06 is approx. 56.5 gr. of Win 760 @ 2800 fps. Max loads in 300 Win Mag require about 70 gr. of powder, while the 300 RUM requires 90-95 gr. to reach max velocity with a 180 gr. bullet.

    My point is this: you need substantial drops in powder to begin to realize any saving in the area of throat erosion. Even the 30-06 burns 18% more powder, but does not suffer from shorter life due to barrel erosion. Most starting loads in reloading manuals for any of the above calibers are only 5% under the listed max loads. To gain any appreciable decrease in barrel wear (such as between the .308 and the 300 Win Mag), you are looking at a decrease in powder of 30% or more. It just isn't practical in light of other factors mentioned previously.
     
  11. TracySes23

    TracySes23 Well-Known Member

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    You & Michael have given me a lot of information to think about. Because of an extreme A.D.D. condition, it takes me a bit longer to retain new information. Been this way since childhood.
    My new rifle will be chambered for the 22-250 & I know I'm not I'm the same league as the guys shooting big bore way beyond 500 yards.
    I want to go to that link you provided & read more. This will help clarify what the two of you have have already told me. I did a number of searches online trying to use different phrases to come up with some leads, with no results. I wasn't even sure I'd get any responses here.

    It appears as though even 4 inches increase in barrel length can't compensate for any realistic drop in charge weight. Another case of diminishing returns
    Since birth (1941) I've always needed to understand things to a degree beyond what most people accept. I don't just want to know the answer, I want to know why. I've never been able to let go of that way of thinking.
    Most people look ay me and think or say, "WTF are you talking about?"
    Clarification in my mind doesn't happen fast for me, but I don't let go until it does.
    My mind has a pattern of wandering off in tangents, so there's more than a fair chance I'll be back with more questions or thoughts.

    Thanks again for the time you two have been willing to take with me.

    Spencer
     
  12. Beng

    Beng Well-Known Member

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    Of course throat erosion will decrease when shooting a low pressure load, compared to hot loads. If your velocity is a constant, a longer barrel and slower burning powders will give you the same velocity at a lower pressure, than a hot load with fast burning powders in a shorter barrel.
    You are asking about a .22-250.
    This case has about the same volume as a .30-30.
    A .22-250 chambered 30" barrel has about the same volume as a 17" .30-30 chambered barrel. Does someone want to say 17" is too long for a .30-30?
    Changing barrel length means always playing with volume, the smaller the caliber your using, the slower pressure will decrease as the bullet runs down the barrel, because volume doesn't increase as fast as in a bigger bore.
     
  13. BountyHunter

    BountyHunter Writers Guild

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    If you are trying to reduce throat erosion, then melonite the barrel. Cost is $100 and way longer barrel life
     
  14. azsugarbear

    azsugarbear Well-Known Member

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    +1 on the meloniting.

    Tracy,

    Regarding your need to understand the "why" of things - that's the reason most of us are here on LRH. And just when you think you have a handle on things, a new line of reasoning comes up and you start the process all over again. We are here because we like to be challenged...we like to learn.