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Thread: Pressure Question GC/PB

  1. #21
    Boolit Master Bazoo's Avatar
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    I think that gas checks would cause an increase in pressure. I expect the percentage of pressure increase to grow with the gas check load when it moves from a reduced load into a full charge load.

    A gas check design bullet without check vs a plain base bullet of the same design I expect would be nearly identical, with the plain base bullet having a slight increase in pressure due to larger driving band surface.

    Thank you Larry for the testing, and thanks for all those that will contribute bullets, time and knowledge to this. It is a furtherment of the understanding of our craft and hobby.

  2. #22
    Boolit Buddy
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    Quote Originally Posted by Bazoo View Post
    I think that gas checks would cause an increase in pressure. I expect the percentage of pressure increase to grow with the gas check load when it moves from a reduced load into a full charge load.

    A gas check design bullet without check vs a plain base bullet of the same design I expect would be nearly identical, with the plain base bullet having a slight increase in pressure due to larger driving band surface.

    Thank you Larry for the testing, and thanks for all those that will contribute bullets, time and knowledge to this. It is a furtherment of the understanding of our craft and hobby.

    Yep, that is exactly what it's all about!


    jd

  3. #23
    Boolit Master
    FredBuddy's Avatar
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    Yesterday, I tested boolits from my new NOE 311-127-FN.

    4 cavity, 2 PB and 2 GC.

    All details of the load identical, except, of course,
    one set with GC, other set with PB.

    POI for GC was 2 inches higher than PB at
    approx 50 yards.

    Certainly NOT SCIENTIFIC, but an observation
    that seems to fit in this thread.

  4. #24
    Boolit Master

    TCLouis's Avatar
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    Hopefully we will get some pressure and precision data out of Larry's gracious help.
    Unlike others in my one attempt I found leaving the GC off lead to significant increase in group size.
    That may well be a boolit to bore diameter issue also.
    So many things can be hidden as to the real reason that one gets a certain result.
    Nothing is impossible for the person that does not have to do it.

  5. #25
    Boolit Master
    Rcmaveric's Avatar
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    I wonder if different gas check materials and designs would change any thing. Like the hornady short copper cups compared to homemade taller aluminum/copper checks.

    Sent from my SM-G950U using Tapatalk
    "Speak softly and carry a big stick; you will go far."
    ~Theodore Roosevelt~

  6. #26
    Boolit Man
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    Ross Seyfried wrote an article titled "Ultimate Cast Handgun Bullets" in Oct of 1993. Among other things, he addressed the Pressure/Velocity of two cast bullets, one plain base and one gas checked. He had two identical 44 caliber, 305gr cast bullet molds cut, one plain base and one GC.

    He had Hodgdon's laboratory test the loaded ammo which was 21.9gr H110, CCI 350, Fed cases, with the following results.

    Gas Check -- 33,300 CUP, 1,383 fps
    Plain Base -- 38,200 CUP, 1,346 fps

    I double checked the results and yes, the GC load was faster at less pressure.

    Would copy the results, but can't figure out how to work with PDF file article.


    FWIW,

    Paul

  7. #27
    Boolit Master Bazoo's Avatar
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    Paul, that is very interesting, thank you for posting.

  8. #28
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    Quote Originally Posted by Paul105 View Post
    Ross Seyfried wrote an article titled "Ultimate Cast Handgun Bullets" in Oct of 1993. Among other things, he addressed the Pressure/Velocity of two cast bullets, one plain base and one gas checked. He had two identical 44 caliber, 305gr cast bullet molds cut, one plain base and one GC.

    He had Hodgdon's laboratory test the loaded ammo which was 21.9gr H110, CCI 350, Fed cases, with the following results.

    Gas Check -- 33,300 CUP, 1,383 fps
    Plain Base -- 38,200 CUP, 1,346 fps

    I double checked the results and yes, the GC load was faster at less pressure.

    Would copy the results, but can't figure out how to work with PDF file article.


    FWIW,

    Paul

    I’d love to see if Larry’s results reflect this as well. I guess the question is, why?

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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