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Thread: Rifleing

  1. #1
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    Default Rifleing

    Hi know nothing about guns. How do they machine the rifeling in the barrel?

    Kev

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  3. #2
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    There are basically 2 main types of rifling :

    1. Button - a button (small cylindrical tool with grooves in in) is pushed/pulled through the barrel and this "imprints" the rifling into the barrel.

    2. Cut - normally a single toothed cutter is again pushed/pulled through the barrel and removes a little metal with each pass. Multiple passes are normally done per rifle groove. A single groove is done at any one time.

    Also note that both systems require the tool to be rotated as it moves down the barrel at the required "twist" rate.

    Barrels are also normally lapped after they have been rifled.
    Cheers.

    Vernon.
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    Thanks.

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    A third method is hammer forged which is often considered the best of the three. This involves having a barrel rifling shaped mandrel(?) inside a barrel of the full unrifled size and belting the carp out of it with mechanical hammers until the inside of the barrel resembles a rifled one. This of course is a very rough description of the process. The hammering relieves the stress in the barrel metal. Also note that some barrels have a variable twist rate just to complicate things.

    Dean

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    Quote Originally Posted by Oldneweng View Post
    Also note that some barrels have a variable twist rate just to complicate things.
    gun smith in NSW also is doing micro rifling with and testing variable twist rates ...

  7. #6
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    With rifling....is the deep part of the groove the diameter of the caliber, or is it the high part (the lands?) which is lapped to the correct calibre?

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    Quote Originally Posted by 19brendan81 View Post
    With rifling....is the deep part of the groove the diameter of the caliber, or is it the high part (the lands?) which is lapped to the correct calibre?
    the greater diameter...ie the deep part

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    To further muddy the waters, let's throw into the mix Polyagonal Rifling.
    This was/is used by several manufacturers most notably Heckler and Koch. The concept was that the bore had no rifling in the conventional sense but was pentagonal or hexagonal in section and this section was twisted along the barrel's length thus inducing the desired rotation to the projectile. The purported benefits were no deformation of the bullet and no sharp grooves to impede smooth air flow over the projectile in flight.
    I believe the barrels were produced by hammer forging.
    Used by several artillery pieces were barrels that were initially rifled but culminated in a smooth bored section that removed the rifling grooves to achieve the same aerodynamic effect.
    Yet another system was the Gerlich. This used a rifled barrel that decreased in diameter, (along with a skirted projectile that could reduce in diameter). This system was pioneered in hunting rifles which produced exceptional velocities for their time, still very respectable today I might add, but was perhaps best know for its use in several German anti tank rifles of the Second World War.
    A bit of trivia for you. How many realise that the good old SMLE, (.303), used a rifling twist which rotated left rather than the standard right? This was due to the fact that when it was designed, the majority of England's wars/actions were in the Southern Hemisphere and the left hand twist was meant to be more accurate due to the coriolis effect, (think how water spins the opposite direction when draining down the plug hole in the North versus the South). The effect was negligible, but the theory was good.

  10. #9
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    Thats interesting info Karl.

    Another thing I have often wondered re rifle barrels is how the hell they drill them out so accurately prior to doing the rifling? Having noticed how far a small drillbit can wander when drilling short distances through plate, ive often thought it must be tough to accurately drill a sub 10mm hole for about 600mm down a rifle barrel. How is this done these days and how was it done in the early days of rifle making?

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    They use a special drill called a "gun drill", interestingly enough.

    Although some of the materials have changed, the principles of drilling barrels hasn't changed a great deal over time.
    Cheers.

    Vernon.
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    Cheers Vernon - interesting process.

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    real early barrels were forged around a mandrel I think...so are some recent if I am correct.
    they then push/pull a button or whatever to cut the rifling

    mate gave me disk showing real persons making an old flint lock from scratch...barrel stock etc etc...no electricity used in the making of the gun except for say lighting or filming

    starts at the forge hammering the crap out of a hunk a steel, then shaping the barrel with a file......if it was me I'd use a mill..seems to me it would have been a whole lot easier if they'd used one

    I'll burn it for those who are interested...i still have it somewhere

  14. #13
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    Quote Originally Posted by 19brendan81 View Post
    With rifling....is the deep part of the groove the diameter of the caliber, or is it the high part (the lands?) which is lapped to the correct calibre?
    It depends. Europeans use bore diameter e.g 7.62 NATO is 7.62 bore 7.82mm groove, .303 is .303 bore but nom.311 groove. Bullet diameter is of course the larger number.

    Americans use groove diameter for calibre e.g .308 win is .308 groove .300 bore . There are exceptions of course; 44magnum has a .429 groove not .44 as the name suggests.

    Garry

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    Default 40mm calibre and above

    I served my time at the Ordnance Factory Maribyrnong and spent some years in the barrel production area from turning trepanning rifleing auto fretaging honing etc can still remember the trepanning settings for a 87 mm bore 350 rpm 2" a minute feed some 26 feet long. maximum drift over that 26 feet was 10 thou We made 40cal 76mm 105mm lepard tank and naval 4.5 inch, from the ingots supplied to us from commsteel J100 was the material spec the waste core bar was highly prized by people doing foreigners at work ie drive shafts for motorcycles etc and the discs that where cut from the ends were used as flywheels all that's gone now though its a housing estate. so sad no more apprentices leave from there was 24 a year Bruce

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    Quote Originally Posted by Garry 3 View Post
    It depends. Europeans use bore diameter e.g 7.62 NATO is 7.62 bore 7.82mm groove, .303 is .303 bore but nom.311 groove. Bullet diameter is of course the larger number.

    Americans use groove diameter for calibre e.g .308 win is .308 groove .300 bore . There are exceptions of course; 44magnum has a .429 groove not .44 as the name suggests.

    Garry
    Years of reading books, magazines etc written by the experts and I have never heard that. Interesting what you can still learn. Thanks for that info. Makes more sense now although the european method is easier to understand but harder to remember.

    Dean

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