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Thread: Bullet - to - cylinder -size and strain on a revolver?

  1. #1
    Boolit Master
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    Bullet - to - cylinder -size and strain on a revolver?

    I was sick and had some extra time to think.

    Now everybody understands the pressure rise with oversize HARD boolits ... but how much do they slam the cylinder forward when swaged through the tight throats? Or do they? Brass sticks to the walls...

    I try to "slip fit" , reamers are in my "tools to get" -list.

    But the question about oversize cast bullets unnecessarily straining the frame,the whole gun,is kinda puzzling me. J-bullets don't do that.

    Thoughts,facts? Too much extra time?

  2. #2
    Boolit Master
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    i wouldn't think the cylinder would forward....more like rearward. think rocket thrust, the path of least resistance is up or out.

    my thoughts.

  3. #3
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    I imagine it varies greatly depending on how oversized a bullet and how hard it is. I would have to think any normal sized bullet within the normal range of sizes won’t be too taxing.

    It’s not that hard to size a bullet down .002, even a hard bullet doesn’t take that much effort. Something .006 oversized and hard is pretty difficult to size down but still doable using my RCBS rockchucker. However a bullet oversized that dramatically probably won’t chamber to begin with.

  4. #4
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    I believe that the cylinder goes backwards, not forwards.
    In order to prevent wear and tear on your revolver, be sure to keep a little oil on the base pin and also on the front and back of the cylinder to act as a cushion during recoil.
    These are the instructions that come with a Linebaugh revolver.

  5. #5
    Boolit Master
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    When a J-bullet is smaller than the throat it's obvious that the brass expands to the cylinder walls and the freely escaping bullet causes the cylinder to slam rearward.

    But when a .002" oversize hard cast bullet enters the throat...? Doesn't it drag the cylinder with itself,slamming it forward? Ignition may kick back first but when the bullet hits the throat...?

    This whole question is quite meaningless. I was just bored in bed.

  6. #6
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    I think you are right but also when the hammer falls it pushes everything forward. When the primer go off it pushed out of the pocket back against the breach. Pressure builds in the case, expanding the case and pushing the bullet into the throat. Nothing yet is creating a force to push the cylinder back against the breach but the cylinder is already forward to the stop so I would not say that the bullet hitting the throat is slamming the cylinder just causing it to push harder forward. Continuing the bullet moves thru the throat and into the forcing cone. Now the cylinder is slammed backward to the breach, reseating the primer.

    Tim
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    Boolit Grand Master tazman's Avatar
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    Quote Originally Posted by dtknowles View Post
    I think you are right but also when the hammer falls it pushes everything forward. When the primer go off it pushed out of the pocket back against the breach. Pressure builds in the case, expanding the case and pushing the bullet into the throat. Nothing yet is creating a force to push the cylinder back against the breach but the cylinder is already forward to the stop so I would not say that the bullet hitting the throat is slamming the cylinder just causing it to push harder forward. Continuing the bullet moves thru the throat and into the forcing cone. Now the cylinder is slammed backward to the breach, reseating the primer.

    Tim
    I think your explanation is exactly right.

  8. #8
    Boolit Master
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    Quote Originally Posted by tazman View Post
    I think your explanation is exactly right.
    I think so too,thank you.

  9. #9
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    Consider opposite and equal reaction. The bullet moving forward and the cylinder moving in the opposite direction.

  10. #10
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    Quote Originally Posted by 6bg6ga View Post
    Consider opposite and equal reaction. The bullet moving forward and the cylinder moving in the opposite direction.
    Or the bullet and cylinder moving forward and the frame and barrel moving backward.

    Tim
    Words are weapons sharper than knives - INXS

    The pen is mightier than the sword - Edward Bulwer-Lytton

    The tongue is mightier than the blade - Euripides

  11. #11
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    What pushes on the frame and barrel to make it go backwards? The Cylinder?
    All of the energy is contained in the catridge, when it fires, the powder burns and is turned into a gas, the gas pushes out all around and the first thing to move is the bullet. As the bullet moves forward, the cylinder moves backward.

  12. #12
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    Quote Originally Posted by lar45 View Post
    What pushes on the frame and barrel to make it go backwards? The Cylinder?
    All of the energy is contained in the catridge, when it fires, the powder burns and is turned into a gas, the gas pushes out all around and the first thing to move is the bullet. As the bullet moves forward, the cylinder moves backward.
    No the first thing to move is the hammer and then the primer backs out of the pocket a bit. Both of which move the cylinder forward and hold it there until the bullet moves into the forcing cone then the bullet acts like a piston in a cylinder and drives the case backward. Depending on the friction between the case and the chamber the cylinder might move backward at this point. Once the bullet is free of the cylinder the cylinder definitely moves backward. If you shoot really light loads you will see the primer protruding from the pocket as the cylinder never moved back to reseat the primer.

    Tim
    Words are weapons sharper than knives - INXS

    The pen is mightier than the sword - Edward Bulwer-Lytton

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  13. #13
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    With bullet sealing the cylinder, and until the bullet physically leaves that cylinder, it's a closed -- and balanced -- system.
    No movement/preferential stress other than normal mv =MV one way or the other due to bullet "strain" on the cylinder throat.

    ...and after the bullet leaves the cylinder, nothing special one way or the other there either.
    the gun hasn't a clue about what the bullet was doing before that time/

  14. #14
    Boolit Master Drew P's Avatar
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    So by that logic there wouldn’t be any recoil felt in the palm, which my palm disagrees with. I’m seeing the logic of balance system except that bullet moving forward, cyl moving backward, because case can’t move backward, so Cyl slams frame, causes felt recoil. However, once energy is transferred to frame, I wonder if the Cyl moves forward again slamming the other side?

  15. #15
    Boolit Master Drew P's Avatar
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    We need a super slow motion camera and a really sloppy pistol lol!

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    Personally, I don't think there is any rearward movement of the cylinder until the bullet exits; jet effect...

    Lots of physics theory going on here. Maybe we need a physicist to figger it out? I think there are some factors that will also influence the whole action/reaction. Time may be one. Since the firing takes only microseconds does the cylinder's mass have time to react before pressure drops to be ineffectual?

    All I know is I cock the hammer on my SBH, pull the trigger and the trigger guard slams against my middle finger. After a few shots I have to wipe the blood off my hand and the gun's grip and stick a band aid on my finger or don a shooting glove...
    Last edited by mdi; 02-20-2020 at 12:19 PM.
    My Anchor is holding fast!

  17. #17
    Boolit Master Drew P's Avatar
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    I’ll work this out with my physicist friend today and report back

  18. #18
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    One might think a hard,fat bullet entering the throat does something differently compared to an undersize bullet.

    But then again one might think Earth is flat.

  19. #19
    Boolit Buddy mehavey's Avatar
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    So by that logic there wouldn’t be any recoil felt in the palm, which my palm disagrees with
    We're talking increased stress on the cylinder due to the bullet being forced through a tight cylinder throat-- while the bullet is still in the cylinder.
    Once the bullet makes it out of the cylinder /into the barrel, it's no longer a closed cylinder system.

    Recoil of the whole System-of-Systems "The Gun" is a whole `nother topic altogether.

  20. #20
    Boolit Grand Master tazman's Avatar
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    That boolit inside the cylinder is being accelerated forward. The same force pushing the boolit forward is pushing the cylinder rearward even if the case has sealed the chamber.
    Equal and opposite forces. As soon as one part begins to move, you get a similar motion in the opposite direction.
    The only force on the sides of the chamber is the pressure generated by the burning powder. That pressure pushes in all directions. The only direction things are allowed to move is forward and backward, in line with the barrel. As the boolit moves forward the cylinder is pushed back until it is stopped by the frame. The frame then recoils with the cylinder as a unit due to the boolit being pushed down the barrel.
    This all begins as soon as the boolit begins to move.
    Think about the old single shot cannon. When that is fired, the ball moves forward and the gun moves rearward. It is just a one hole cylinder.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check