Performance Firearms and Thermodynamics. Parts I & II - Page 4
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Thread: Performance Firearms and Thermodynamics. Parts I & II



  1. #31
    Gun Wizard
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    That's a lot of accurate lead flying downrange..!!

    If these guys ( and Gal ..! ) had been the shooters for the old Chicago gangs, Elliot Ness would have had a much shorter career there..!!
    Team 22 Magnum ! #008

  2. #32
    Gun Wizard
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    Oh yea...liked the music..!!
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    Team 22 Magnum ! #008

  3. #33
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    Quote Originally Posted by Wild Turkey View Post
    Isn't heat dissipation part of the reason machine guns often fire from the "open bolt" position so that air can pass through the barrel when not firing?
    WT, your question does illuminate an interesting point about typical firearms. Aside from full autos firing from an open bolt, most guns effectively plug the bore with a fresh cartridge. The column of heated air inside the bore becomes the nemesis of heat dissipation, rapidly "saturated" with heat, and with near-zero circulation, it becomes a perfect insulator, preventing heat from leaving except through the barrel steel itself, to the outer surface.
    Ranger Point Precision (Houston, TX) - Lever Action expert, Precision Gunsmith and Machine Shop. We custom-build lever action, AR15 and long range rifles and we design and manufacture Marlin, Henry and Steyr A1 Pistol parts (medium loop levers, day & night sights, scope mounts, dovetail fillers, full-length 444 mag tubes, and more). Some of our best sellers are our Marlin 1894 Pistol Caliber, Short Strokes (9mm, 10mm, 327 Fed/32 H&R, .40 S&W, .44 RIPSAW, .45ACP, .45 Cowboy, .357 SIG and more); Marlin 410 Lever Action Shotgun; Marlin 336 36 RPP (big brother to the 35 Rem); Marlin 336 Ackley Improved and Ackley eXtreme for .308ME handloads (or 7-30 Waters, 38-55, 25-35); Hand-Built 6.5mm Grendel AR-15 Rifle; performance gunsmith services of all kinds from match grade barrel swaps to trigger & action jobs, accurizing, barrel shortening/threading/porting and muzzle brakes along with KG Gun Kote and Duracoat metal coatings and wood refinish work.

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  5. #34
    Sidewinder
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    "the additional energy needed to spin a bullet faster will manifest as extra heat in the bore,"

    As you obviously know, the need for energy has never generated heat (other than political heat and pressure I suppose).

    You might be saying that additional fuel manifests as additional heat in the barrel, but that's too obvious.

    It would be interesting to contemplate exactly how much heat is contributed to the barrel by various events. For example, increasing the twist rate increases bullet deformation which heats the barrel. Increasing the twist rate increases the surface that the bullet must traverse, increasing total friction and therefore barrel temp. A heavier bullet or a faster twist will increase the time the bullet is in the barrel which increases the time that the hot gases are in contact with the barrel heating the barrel.

    i recognize that you're thinking about how to eliminate heat, but it might be productive to think about how to avoid some of it as well.

    Thanks for the interesting discussion,
    Jim
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    I've always thought gain twist rifling was a cool idea. No pun intended. It would seem to have more than one advantage, but maybe it's just not cost effective. The only commercial application I'm aware of is the S&W .460. Might be an interesting conversation with my barrel maker next time I'm on the phone with them.
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    Ranger Point Precision (Houston, TX) - Lever Action expert, Precision Gunsmith and Machine Shop. We custom-build lever action, AR15 and long range rifles and we design and manufacture Marlin, Henry and Steyr A1 Pistol parts (medium loop levers, day & night sights, scope mounts, dovetail fillers, full-length 444 mag tubes, and more). Some of our best sellers are our Marlin 1894 Pistol Caliber, Short Strokes (9mm, 10mm, 327 Fed/32 H&R, .40 S&W, .44 RIPSAW, .45ACP, .45 Cowboy, .357 SIG and more); Marlin 410 Lever Action Shotgun; Marlin 336 36 RPP (big brother to the 35 Rem); Marlin 336 Ackley Improved and Ackley eXtreme for .308ME handloads (or 7-30 Waters, 38-55, 25-35); Hand-Built 6.5mm Grendel AR-15 Rifle; performance gunsmith services of all kinds from match grade barrel swaps to trigger & action jobs, accurizing, barrel shortening/threading/porting and muzzle brakes along with KG Gun Kote and Duracoat metal coatings and wood refinish work.

  7. #36
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    Have you explored micro crystalline aluminum nitride as an interior coating?
    It seems to be the only modification available to increase heat dispersion from within, absent any airflow.
    Virtually weightless and esthetically invisible, much improved wear resistance.
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    Ha dilchali- Ayaats'iin

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    Quote Originally Posted by RangerPointPrecision View Post
    I've always thought gain twist rifling was a cool idea. No pun intended. It would seem to have more than one advantage, but maybe it's just not cost effective. The only commercial application I'm aware of is the S&W .460. Might be an interesting conversation with my barrel maker next time I'm on the phone with them.
    Hey Adam,

    As far as I know, Schuemann still makes .45 acp barrels for the 1911, with "gain twist"?

    Later, Mark
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  9. #38
    Sidewinder
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    I like the concept of gain-twist barrels for a couple reasons and also expect that they would heat more evenly and have longer life, but I don't remember them being exactly economically viable.

  10. #39
    Sidewinder
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    When things got hot, the old buffalo hunters would just pee down the bore.
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  11. #40
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    Quote Originally Posted by RangerPointPrecision View Post
    I've always thought gain twist rifling was a cool idea. No pun intended. It would seem to have more than one advantage, but maybe it's just not cost effective. The only commercial application I'm aware of is the S&W .460. Might be an interesting conversation with my barrel maker next time I'm on the phone with them.
    Back when I still worked, the barrels (mostly military) we manufactured had a gain twist; starting with a straight run and becoming faster as it moved down the length. Can't remember for sure, but believe part of the reason for that gain was to help better stabilize a bullet/projectiles designed with "sealing bands" that engaged the rifling; probably to help limit deformation/damage of those bands initially as well? I also recall something about it limiting the potential of what they called "porpoising" (think Dolphin swimming) of the projectile as it moved down the barrel. If still working, I'd ask the design engineers to refresh my memory on all the specific details again, ha!
    Anyway, employing a gain twist in the making/rifling of a barrel didn't add to the cost any, at least not to us, but might depend on the type of equipment or method a given manufacturer may have to use.
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