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Thread: 300blk - Subsonic in Rattler "outperforms" BCM 9in

  1. #21
    Quote Originally Posted by Cool Breeze View Post
    I don't know anything about ballistics so forgive me in advance. This just came out today. MAC suggests that subsonic will tumble out of the Rattler creating better terminal ballistics vs. zipping right through from the 9inch. No idea how watermelons stack up to ballistic gel or human tissue, but I was thinking about a Rattler or a 9inch AR pistol lately and I thought it might be interesting to discuss the ballistics of it all (subsonic and supersonic).

    https://www.youtube.com/watch?v=rTxhMFqzqV0
    Might be worth it...

    The Hornady 'subbie' offering looks to offer some pretty decent performance:

    Name:  Hornady .300AAC 190-gr Sub-X TAP.jpg
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    ''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein

    Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.

  2. #22
    Quote Originally Posted by the Schwartz View Post
    Might be worth it...

    The Hornady 'subbie' offering looks to offer some pretty decent performance:

    Name:  Hornady .300AAC 190-gr Sub-X TAP.jpg
Views: 1569
Size:  86.5 KB

    What does this bring to the table ballistically compared to quality service caliber pistol rounds?

    I can see better expansion relative to diameter and the high sectional density likely provides very consistent penetration.

    Thanks for all your input.

  3. #23
    Site Supporter Sensei's Avatar
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    Quote Originally Posted by Navin Johnson View Post
    What does this bring to the table ballistically compared to quality service caliber pistol rounds?

    I can see better expansion relative to diameter and the high sectional density likely provides very consistent penetration.

    Thanks for all your input.
    As others have said, itÂ’s the ability to insert a magazine loaded with these rounds once a supersonic crack is no longer an issue:

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    The ability to shoot sentries in the head with a reasonably lethal subsonic round on infiltration, and then be able to immediately switch to a supersonic round with outstanding barrier penetration on exfiltration is very desirable to some parts of our military.

    For civilians, even the best subsonic loads should only be used for things like nighttime hunting when you donÂ’t want to wake the neighbors. ItÂ’s fine for coyotes or boar. However, IÂ’d never take a subsonic load over the Barnes 110 grain black tip when my life is on the line.
    Last edited by Sensei; 08-24-2020 at 12:49 AM.
    I like my rifles like my women - short, light, fast, brown, and suppressed.

  4. #24
    Site Supporter Odin Bravo One's Avatar
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    As some of you may know, I don’t give a fuck what gelatin test results look like. I care what meat and bone testing results look like. They are different often enough that the former holds very little sway over my ammunition selection decisions.

    I’ve only used 110 TTSX and 220 OTM subs for social work, and if given the choice, I’ll take the subs all day.

    The 110’s do a lot of damage to be sure. But they don’t suppress well, for what (I hope) are obvious reasons. The subs often don’t look terribly impressive on paper or in gel but the results they produce when popping skulls open is undeniable, and they are substantially quieter than their supersonic half-weight counterparts.

    Since most infantry engagements are inside 200 yards, and most civilian engagements are substantially closer than that, the terminal differences between subs and supers are negligible. As for “outperforms” claims, according to who and in what capacity? When it comes to shooting assholes, If you can shoot, whatever you are shooting will outperform the ammunition being used by people who can’t shoot.
    Last edited by Odin Bravo One; 08-24-2020 at 06:54 AM.
    You can get much more of what you want with a kind word and a gun, than with a kind word alone.

  5. #25
    Quote Originally Posted by the Schwartz View Post
    Might be worth it...

    The Hornady 'subbie' offering looks to offer some pretty decent performance:

    Name:  Hornady .300AAC 190-gr Sub-X TAP.jpg
Views: 1569
Size:  86.5 KB

    Quote Originally Posted by Navin Johnson View Post
    What does this bring to the table ballistically compared to quality service caliber pistol rounds?

    I can see better expansion relative to diameter and the high sectional density likely provides very consistent penetration.

    Thanks for all your input.

    As a projectile expands in 10% ordnance gelatin or in human soft tissues, erosion kinematics briefly governs its behavior as a Bernoulli interface-stress balance expressed as ½ρ(V-U)² + YR = ½ρU² + RT within that regime. In the Bernoulli equation, V is the projectile's impact velocity and U is the nose-target interface velocity which is determined by the square root of the ratio of target to projectile densities. YR and RT are projectile and target yield strengths respectively. After the expansion/erosion regime ends, post-expansion projectile length dictates penetration depth in terms of a Poncelet flow regime expressed as X = LN(Vo/Vcritical)(SD/CD).

    Since subsonic rounds are limited in terms of their maximum velocity (< 1,000 fps), the projectile's momentum must be increased to drive a fully expanded projectile deeper while retaining greater instantaneous velocities at depth. Increasing a projectile's momentum is most easily accomplished by increasing its mass. In both flow regimes, maximum terminal penetration depth is extremely sensitive to projectile length so a heavier—and commensurately longer—projectile afforded by larger (rifle) case length that allows for deeper seating of longer projectiles without impinging upon propellant volume makes sense. Even at subsonic velocities, greater post-expansion length (sectional density) equates to greater terminal penetration depth and higher velocities at depth.

    Compared to service pistol-caliber rounds?

    The larger case volume and length of rifle cases can launch significantly longer and heavier projectiles which means that post-expansion length (sectional density) surpasses that of the lighter, and much shorter, projectiles that are mandated by the limited case volumes available in service pistol-caliber cartridges. In addition to greater penetration depths, greater post-expansion sectional density (length) also means that the projectile retains higher velocity at those depths translating to greater strain energy storage within the tissues surrounding the bullet's path and increasing the likelihood of tissue damage needed to produce incapacitation.
    Last edited by the Schwartz; 08-24-2020 at 10:14 AM.
    ''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein

    Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.

  6. #26
    Gray Hobbyist Wondering Beard's Avatar
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    Quote Originally Posted by Giving Back View Post
    As some of you may know, I don’t give a fuck what gelatin test results look like. I care what meat and bone testing results look like. They are different often enough that the former holds very little sway over my ammunition selection decisions.

    I’ve only used 110 TTSX and 220 OTM subs for social work, and if given the choice, I’ll take the subs all day.

    The 110’s do a lot of damage to be sure. But they don’t suppress well, for what (I hope) are obvious reasons. The subs often don’t look terribly impressive on paper or in gel but the results they produce when popping skulls open is undeniable, and they are substantially quieter than their supersonic half-weight counterparts.

    Since most infantry engagements are inside 200 yards, and most civilian engagements are substantially closer than that, the terminal differences between subs and supers are negligible. As for “outperforms” claims, according to who and in what capacity? When it comes to shooting assholes, If you can shoot, whatever you are shooting will outperform the ammunition being used by people who can’t shoot.
    Did you use barrels as short as the Rattler's 5.5" with subs?

    It would seem that the velocity loss could really affect things, but I have no experience with either.
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  7. #27
    Site Supporter Odin Bravo One's Avatar
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    Barrel length may make a difference on marginal hits (i.e., shitty shot placement). But I’ll lay dollars to pesos that if you drill them between the running lights, things like barrel length, subs versus supers arguments become irrelevant. But that’s my opinion, and worth what you paid for it.
    You can get much more of what you want with a kind word and a gun, than with a kind word alone.

  8. #28
    Site Supporter entropy's Avatar
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    Crap. I signed up to this thread as an elective. I didn’t know math was required.

    I’m outta here!
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  9. #29
    Quote Originally Posted by entropy View Post
    Crap. I signed up to this thread as an elective. I didn’t know math was required.

    I’m outta here!
    Basket-weaving and pottery class is down the hall, first classroom on the left past the custodian's closet. If you go past that, you'll end up in Poli-Sci class and you'll be on your own there. /kidding

    No real heavy math is needed. Don't let the equations bug you. Simply put, there are two regimes. Hydrodynamic regime is the first, where the projectile material flows/deforms under pressure like a liquid. After that is the Rigid/Static regime, where expansion stops, momentum decreases until the projectile comes to a stop. That's what the equations say, just in ''Nerd-ese''.
    ''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein

    Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.

  10. #30
    Member SecondsCount's Avatar
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    Quote Originally Posted by entropy View Post
    Crap. I signed up to this thread as an elective. I didn’t know math was required.

    I’m outta here!
    Well, I think professor Giving Back just made it easier on you. It would seem that while the math and science are useful, what counts is time on the range so you can hit the target where it counts
    -Seconds Count. Misses Don't-

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