Barrel stiffening

Discussion in 'General Airgun Chat' started by Chris58b, Aug 23, 2015.

  1. Chris58b

    Chris58b Member

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    I've been reading on various websites about barrel stiffening and the theory that its supposed to dampen barrel vibrations and improve accuracy. As I've not heard of this mod before I was wondering if anyone on here has tried stiffening a barrel with a tight fitting carbon sleeve bonded in place with epoxy? If so, were there any accuracy improvements.
    Regards,
    Chris
     
  2. saddler

    saddler Phil Gee

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    I personally don't think stiffening the barrel will automatically improve accuracy.
    By adding weight, changing stiffness, adding or removing barrel supports, what you are effectively doing is changing the natural frequency of the barrel.
    I'm not sure, but I think what you're looking to do is to create a node point at the end of the barrel, I.e. Have a point at which the barrel is neither moving up or down, so that the pellet leaves the barrel with no off centre forces acting on it.
    That can be achieved by increasing stiffness or by reducing stiffness, adding mass at various points along the barrel, or removing mass, increasing the grounded locations (I.e. Barrel supports) or removing them. It will be different for every barrel.
    The only way you'll know for sure is to try it.
    By the way, I think a lot of the positive effect of many muzzle flips is the damping characteristics that come from their mass rather than their air stripping ability.
     
  3. Chris58b

    Chris58b Member

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    Thanks for the response Saddler.
    Yeah, having the node point at the muzzle/crown is regarded as the optimum and is usually achieved with barrel tuners. However, the bofffins also say that stiffening the barrel will reduce the vibrations all along the barrel including at the muzzle/ crown but to a lesser extent than the tuner. It seems to be quite a popular mod in America.
    Like you say I think I'll need to try it. My barrel is 14mm od and I already have a carbon sleeve which is 18mm od x 16mm id. So I've ordered a 16mm od x 14mm id which should be a tight fit between the barrel and the shroud. I'll try this with just a friction fit and see if it offers any improvement. If it does I'll then need to decide if I'm gonna bond it on with epoxy for additional stiffness.
    Regards,
    Chris
     
  4. saddler

    saddler Phil Gee

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    The problem with any dissimilar materials? Expansion rate...
    That's why barrel bands are a good idea in principal and calculation but not in practice...
     
  5. Chris58b

    Chris58b Member

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    Yeah, that's a valid point.
    I only shoot benchrest in an indoor heated range so don't really experience any significant temp fluctuations. However, I'll keep an eye out for any temperature related patterns before committing to any bonding plans. At this stage it will be easily reversible and makes a nice change from chasing the mythical "perfect pellet" :)
    Regards,
    Chris.
     
  6. Ratinator

    Ratinator 77.74

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    too tight

    If your carbon sleeve is to tight a fit to go on the barrel ,i think I read that if it's put in the freezer it expands not contracts . May just get you that little extra required.
     
  7. Chris58b

    Chris58b Member

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    Top tip Ratinator, the sleeve is likely to be a tight fit to this might be very useful to know. Cheers.
     
  8. hmangphilly

    hmangphilly The Doctor

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    that's easy to test....

    shoot it with the device .......
    remove device....
    attach equal weight to end of barrel .....self adhesive wheel balancing weights are ideal.
    shoot with device removed but weights fitted .......

    chris58b....what rifle are we talking about ? ........others here may have barrel experiences to share.
     
    Last edited: Aug 24, 2015
  9. Chris58b

    Chris58b Member

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    chris58b....what rifle are we talking about ? ........others here may have barrel experiences to share.[/QUOTE]

    Sorry, forgot to mention I'm shooting an FTP 900 with no reg problems( 3-4 fps & no reg creep)
    Regards,
     

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