scope expansion

Discussion in 'Competition Forum (All Calibers)' started by Alex Wheeler, Oct 29, 2016.

  1. JRS

    JRS Silver $$ Contributor

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    When you have that level of experience and expertise, get back with us;)
     
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  2. LHSmith

    LHSmith

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    Nope. As Alex mentioned, molecules expand in EVERY direction when heated/ even though you are visualizing the inner walls moving inward, you are negating the fact that the outer walls are moving outward also....the net result is the ID actually becomes larger.
     
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  3. LHSmith

    LHSmith

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    That was my attempt to get him to remember heat = grows and cold = shrinks by association with everyday things and a bit of humor.
     
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  4. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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  5. Ledd Slinger

    Ledd Slinger Gold $$ Contributor

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    I had to 'unignore' JRS to see what you guys were talking about here. Didn't take much reading to remember why I had JRS on that list :rolleyes:
     
  6. JRS

    JRS Silver $$ Contributor

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    Wrong again. The inner wall is increasing in diameter, meaning, outward. Like I said, drill a hole in a piece of plate and apply heat to that piece of plate. The plate isn't going to grow. The hole size will increase. As a barrel heats up, due to the dead end in the action, the barrel is going to increase in length. As an objet increases in length, it decreases in diameter. Kinda like a piece of glass subjected to heat. If that glass is 1/8" thick, once subjected to enough heat, the glass will shrink and pull in to be 1/4" thick. If you start out with 3/8" thick glass, it will expand to pool out so that it is only 1/4" thick. Much like glass, the atoms in steel prefer to be a certain thickness before starting to change direction.
     
  7. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    I must admit, I really do not think there is much accuracy to be found in thermal expansion issues regarding a rifle. I never really did. BUT, I did think it could be an interesting discussion and maybe I would learn something I never considered. Thats why I started it the way I did, to see where it would go. Thought it would be a little more interesting than the same old what scope for my deer rifle threads. It does have some good comedic content though lol. Its getting tougher to have intelligent conversation I guess.
     
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  8. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Who ever hacked JRS's account, stop F-ing with us!
     
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  9. tom

    tom Gold $$ Contributor

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    Caught him!

    th (1).jpg
     
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  10. JRS

    JRS Silver $$ Contributor

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    Tell me, Alex. How much experience do you have designing and manufacturing optical glass and scopes.
     
  11. LHSmith

    LHSmith

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    Good riddance.:rolleyes:
     
  12. LHSmith

    LHSmith

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    Nope...he's the real deal.
     
  13. JRS

    JRS Silver $$ Contributor

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    Forget about the Jiggery-pokery and Chinese alphabet soup. Step into the world of reality;) I can take a torch, heat and shrink a crooked section of handrail to make it as straight as a needle. It isn't going to grow.

    Edit: Without actual experience, it's easy to believe what you have read, or have heard, without actual hands-on experience.
     
    Last edited: Jan 10, 2018
  14. Papa Charlie

    Papa Charlie Silver $$ Contributor

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    That is not the reason the bore increases, it is increasing as there is no place for the molecules to go they have to expand outwards not inwards. Think of the arch supporting a doorway in a wall. Expansion has to move outward.
     
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  15. JRS

    JRS Silver $$ Contributor

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    That is exactly what the bore does. It moves outwards, (increasing) though the OD really doesn't change. If the framework of the door expanded outwards, the drywall would crack. That is my reason for the reactor vessel scenario. Only the ID can expand. What happens when you fire form brass with a tight fit in the chamber? The ID increases.
     
    Last edited: Jan 10, 2018
  16. Stan Taylor

    Stan Taylor

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    Damn Tom I used to get one of them man time flies from you were young dumb an full of _ _ _ you can fill in the blanks very interesting assumptions though it is confusing me a little though but definitely interesting to say the least.
     
  17. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    I learned something today at least, barrels get longer when heated but bridges shrink. Who'd a thunk it?
     
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  18. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Stan, skip the stress relieving process and turn the blank down. Bet the bore grows on that one. PS your the one supposed to be teaching us. They threw me out after 10th grade.
     
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  19. dkhunt14

    dkhunt14

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    If this was the case I would see a drop off in velocity. I never saw that. I believe accuracy falls off because the heat makes the barrel move. Matt
     
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  20. Jay Christopherson

    Jay Christopherson it's turtles, all the way down Administrator

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    OK, we need to stop with the notions that cold somehow causes expansion, heat causes contraction, and the earth is flat. :rolleyes: There are plenty of sites out there that deal in fantasy. I bet Neil DeGrasse Tyson would happily disabuse you of all three of those notions, if you want to go pester him about it.

    EDIT: Though I will stipulate the existence of Negative Thermal Expansion, though the use cases are pretty rare.
     
    Last edited: Jan 10, 2018

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