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Thread: Measuring 5 groove rifling

  1. 06-20-2022, 01:03 PM #1
    GBertolet
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    Measuring 5 groove rifling

    What is the prefered way to measure the 5 groove S&W rifling? I tried two methods. First pinching a piece of thin shimstock around the bullet, then measure the diameter, and subtract twice the thickness of the shimstock. The resulting figure will be your diameter. Secondly, place a bullet or pin gauge of known diameter in a V block. Measure from the top of the bullet, to the underside of the V block. Deduct the diameter of the bullet from this figure, and write down the difference. This will be your base measurement. Place the bullet to be measured in the V block. Measure the total from the top of the bullet to the underside of the V block, and deduct your base measurement. This will supposedly be your bullet diameter.

    On my 16-4, 32 mag S&W, I got the same measurement, using both methods. I got .309, which I am having trouble believing is correct, as it is so small. My cylinder throats measured .311, with a pin gauge, so I know that is correct. At least the cylinder throat to groove diameter relationship seems to be correct.
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  2. 06-20-2022, 01:41 PM #2
    Der Gebirgsjager
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    Almost the same as your first method is to slug the barrel, wrap the slug, measure, subtract twice the thickness of the wrap.

    DG
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  3. 06-20-2022, 02:22 PM #3
    M-Tecs
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    The preferred method is with a 108 v-mic. I purchased a Shars 0.2-1" 108 Degree 5 Flutes Measured V-Anvil Micrometer .0001" 303-2346 P on Amazon for about $75.00 but they currently are not available.

    Some other options and issues here:

    http://www.texas-mac.com/Measuring_G...ove_Bores.html
    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

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  4. 06-20-2022, 07:58 PM #4
    Nobade
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    What he said. I had need to measure throating reamers which are mostly all 5 flute, so found a nice Mitutoyo V anvil mic on Ebay. Someday hopefully will find one for measuring 7 flute objects as well.
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  5. 06-21-2022, 03:23 AM #5
    M-Tecs
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    Quote Originally Posted by Nobade View Post
    What he said. I had need to measure throating reamers which are mostly all 5 flute, so found a nice Mitutoyo V anvil mic on Ebay. Someday hopefully will find one for measuring 7 flute objects as well.
    I did the same since I am not a big fan of the Chinese stuff. The Mitutoyo that I found went cheap at $44.00 and it in very good shape but doesn't have .0001" graduation. The Shars surprised me. It checks out very well on Deltronic pins.
    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

    "Before you argue with someone, ask yourself, is that person even mentally mature enough to grasp the concept of different perspectives? Because if not, there’s absolutely no point."
    – Amber Veal

    "The Highest form of ignorance is when your reject something you don't know anything about".
    - Wayne Dyer
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  6. 06-21-2022, 06:48 AM #6
    Nobade
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    Thanks, good to know! Funny, I just subscribed to their propaganda yesterday and ordered a catalog. Got to get the new shop up and running.
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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