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Thread: Question: When Does a Pistol Caliber Become a Rifle Caliber?

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    Question: When Does a Pistol Caliber Become a Rifle Caliber?

    All,

    As is often said, "pistols are pistols and rifles are rifles". But at what point does a pistol caliber become a rifle caliber?

    Let's compare four self-defense loads:

    Federal LE Tactical HST JHP
    9mm Luger +P
    124 gr
    1200 fps
    396 ft-lbs
    https://www.luckygunner.com/9mm-p-12...st-1000-rounds

    Federal LE Tactical HST JHP
    .45 ACP
    230 gr
    950 fps
    461 ft-lbs
    https://www.luckygunner.com/45-acp-2...nt-1000-rounds

    Federal LE Tactical SP
    .223 Remington
    55 gr
    3220 fps
    1266 ft-lbs
    https://www.luckygunner.com/223-rem-...tru-500-rounds

    Federal Fusion SP
    7.62x39
    123 gr
    2350 fps
    1508 ft-lbs
    https://www.luckygunner.com/7-62x39m...sion-20-rounds

    MUZZLE ENERGY --> LETHALITY

    There's a clear difference in muzzle energy. The .223 bullet is less than half the size of the 9mm bullet, but because it's going nearly 3x as fast, it's going to be more lethal:


    https://www.ar15.com/ammo/project/Se...ense_Ammo_FAQ/

    Is there a point at which a pistol caliber becomes a rifle caliber in terms of muzzle energy? Is there an accepted standard, e.g. "Any bullet that delivers more than 1000 foot-pounds energy is no longer a pistol caliber, but a rifle caliber"?

    SPEED --> FRAGMENTATION

    There's a clear difference in feet per second. It's been well-documented that misses from faster rifle bullets are less likely to pose a danger to others:

    "Statements are made that the shotgun or pistol should be used because of the over-penetration problem with 5.56 carbine ammunition. This could not be further from the truth. If you conduct a little research you will find that numerous law enforcement departments, to include the FBI, have proven this to be false in most cases. The fact of the matter is that many of these bullets will penetrate numerous walls, but standard 5.56 loadings are the least of your worries when compared to pistol and shotgun fodder, which continue to take top honors in the category of over-penetration." US Army Sergeant Major Lamb (former Delta/CAG)
    https://www.americanrifleman.org/art...xperts-opinion

    "Common pistol rounds easily penetrated all 4 walls spaced out at room distances. This is a critical issue. Think about the inside of your house and imagine if you shot through 4 walls. Could you hit a loved one? Know your target and what is behind it....The 5.56 rounds deviated greatly from the original flight path once they started tumbling. This occurred after the second wall." Old_Painless (certified Pistol, Rifle, Shotgun, Personal Firearms Defense, and Home Firearms Safety Instructor)
    http://www.theboxotruth.com/the-box-...sulated-walls/

    "Proponents of the pistol for home defense like to think that because it’s 'just' a pistol round, overpenetration really won’t be an issue. Such is not the case. Drywall sheets and hollow-core doors (which are what you’ll find in the majority of homes and apartments in this country) offer almost no resistance to bullets....For years many people just assumed they knew what would happen to a rifle bullet fired indoors—it would go through every wall available and then exit the building. While armor-piercing and FMJ ammunition is specifically designed to do this, extensive testing has shown that light, extremely fast-moving .223 projectiles (including FMJs) often fragment when they hit a barrier as soft as thin plywood." James Tarr (former police officer; contributing editor for Guns and Ammo)
    http://www.gunsandammo.com/ammo/long...fense-caliber/

    "The .223/5.56 is moving at around 3,000 feet per second, and while it isn’t magic bullet, it’s a far cry better than any pistol round. Another advantage of the .223/5.56 is its limited penetration. The shape and velocity of the round cause it to immediately expend or dissipate its energy once it strikes something." Tiger McKee (adjunct instructor at Thunder Ranch)
    https://gundigest.com/reviews/ar-15-...e-defense-guns

    "The pistol rounds were seemingly unaffected by the drywall and/or wood barriers. There was no observable deviation or fragmentation of the 9mm projectiles. You’d be safe counting on a pistol round to keep going, and going, and going. After all, premium pistol ammunition is designed to expand, and lose energy, when striking liquid-based targets—not walls. The full metal jacket .223 rounds tended to tumble rather than break apart when they encountered barriers." Tom McHale (contributor at AmmoLand and OutdoorHub)
    http://www.outdoorhub.com/stories/20...ration-issues/

    "FBI and Independent Testing Has Consistently Shown .223/5.56 NATO Fired From AR-15’s Do Not Over Penetrate More Than Pistol/Shotgun." Caleb Lee (NRA Certified Basic Pistol & Personal Protection Inside The Home Instructor)
    http://preparedgunowners.com/2016/07...ation-testing/

    "Since all of the 5.56 mm/.223 bullets fired through the interior wall had significantly less penetration than 9 mm, .40 S&W, .45 ACP, and 12 ga. shotgun projectiles which were fired through an interior wall, stray 5.56 mm/.223 bullets seem to offer a reduced risk of injuring innocent bystanders and an inherent reduced risk of civil litigation in situations where bullets miss their intended target and enter or exit structures. As such, 5.56mm/.223 caliber weapons may be safer to use in CQB situations and crowded urban environments than service caliber handguns or 12 ga. weapons." Dr. Gary Williams (ballistics expert)
    http://www.recoilweb.com/ar-vs-shotg...#ixzz4zCOCPykZ
    Those who subscribe to this principle believe that if you're concerned about overpenetration, the faster (and smaller) .223 is better for home defense than the slower (and bigger) 7.62x39 (and of course, better than even slower [and even bigger] pistol rounds).

    Is there a point at which a pistol caliber starts to behave like a rifle caliber in terms of speed? Is there an accepted standard, e.g. "Any bullet that travels more than 2000 feet per second is no longer a pistol caliber, but a rifle caliber"?

    Respectfully,
    butlers
    "The nation that will insist on drawing a broad line of demarcation between the fighting man and the thinking man is liable to find its fighting done by fools and its thinking done by cowards."
    William Francis Butler

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    Is there a point at which a pistol caliber starts to behave like a rifle caliber in terms of speed?
    It's a sliding scale for sure but the stretch cavity that rifles produce, as opposed to pistol round, generally occurs around the 1,900-2,200 FPS range

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    Quote Originally Posted by Mrgunsngear View Post
    It's a sliding scale for sure but the stretch cavity that rifles produce, as opposed to pistol round, generally occurs around the 1,900-2,200 FPS range
    This. Shotgun slugs make rifle-ish temp cavities around 1800fps because of the large surface area and mass.
    As projectiles get smaller, the velocity has to increase.
    .224-.30 is around 2000fps or so.

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    Quote Originally Posted by MegademiC View Post
    This. Shotgun slugs make rifle-ish temp cavities around 1800fps because of the large surface area and mass.
    As projectiles get smaller, the velocity has to increase.
    .224-.30 is around 2000fps or so.
    Bingo! It's not as simple as upping velocity = rifle-like terminal ballistics. The SHAPE of the projectile matters alot. Take a look at 19th century lever gun ballistics, cartridges like the .45-70 in historical bullet weights are almost always traveling below the magic 1900-1800 fps and produce rifle like temporary stretch cavities. Now shoot a .30 cal steel BB at 4000 fps into gel and you almost no temporary stretch cavity.

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    Quote Originally Posted by vicious_cb View Post
    Bingo! It's not as simple as upping velocity = rifle-like terminal ballistics. The SHAPE of the projectile matters alot. Take a look at 19th century lever gun ballistics, cartridges like the .45-70 in historical bullet weights are almost always traveling below the magic 1900-1800 fps and produce rifle like temporary stretch cavities. Now shoot a .30 cal steel BB at 4000 fps into gel and you almost no temporary stretch cavity.
    Yes. Upset is a huge factor. Iirc Doc said they pushed .22” projectiles around 7,000fps and they made pin-holes because there was no upset. Each bullet has its own behavior, the mass/diameter/velocity gives it good potential.

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    Quote Originally Posted by MegademiC View Post
    Yes. Upset is a huge factor. Iirc Doc said they pushed .22” projectiles around 7,000fps and they made pin-holes because there was no upset. Each bullet has its own behavior, the mass/diameter/velocity gives it good potential.
    His test methodology must have been off.


    a .22 at 7,000 fps is a miniature nuke.

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    Quote Originally Posted by turnburglar View Post
    His test methodology must have been off.


    a .22 at 7,000 fps is a miniature nuke.
    No thats 10mm. Here is the scientific proof.


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    Quote Originally Posted by turnburglar View Post
    His test methodology must have been off.


    a .22 at 7,000 fps is a miniature nuke.
    No his methodology was sound, they were testing extreme velocities with rounds designed to not upset iirc.
    .. but please do continue about how DocGKR is not properly performing terminal ballistics testing.

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    Quote Originally Posted by MegademiC View Post
    No his methodology was sound, they were testing extreme velocities with rounds designed to not upset iirc.
    .. but please do continue about how DocGKR is not properly performing terminal ballistics testing.
    Save your sanity and dont bother arguing with people so far out of touch with reality. It isnt worth it.

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    Thank you all for your input.

    I enjoy introducing firearms to new shooters, and I run an informal class on the differences between pistols, rifles, and shotguns. With the advent of atypically high-velocity pistol rounds and atypically low-velocity rifle rounds, I'm having a difficult time distinguishing between the two.

    For example, let's say you're a range master at an indoor pistol range.
    - One shooter comes in with his 10.5" suppressed 300 BLK SBR.
    - The other shooter comes in with his 16.0" 10mm pistol caliber carbine.
    - The first guy shoots a Hornady "A-MAX" 300 BLK bullet -- it's 208gr traveling at 915 fps (out of a 10.5" barrel) = 387 ft-lbs muzzle energy.***
    - The second guy shoots a Liberty "Civil Defense" 10mm bullet -- it's 60gr traveling at ~2793 fps (out of a 16.0" barrel) = 1039 ft-lbs muzzle energy.###

    You're the range master. Do you stop the first guy, the second guy, both, or neither? How do you justify/articulate your judgement call? Do you cite bullet weight? Velocity? Muzzle energy? Shape (i.e. spitzer vs non-spitzer)? Remember, one is shooting 300 BLK (originally designed as a rifle round) out of a short barreled rifle (but it's performing like a pistol); the other is shooting 10mm (originally designed as a pistol round) out of a pistol caliber carbine (but it's performing like a rifle).

    Things that make you go "hmmm...."



    P.S. My math:

    ***These figures are from this test:
    https://www.shootingtimes.com/editor...mmo-test/99395

    ###These figures are estimated from this data:
    http://10mm-firearms.com/factory-10m...60gr-2400-fps/
    http://ballisticsbytheinch.com/10mm.html

    10mm 60gr tests
    - 4.75" barrel = 2511.5 fps
    - 6.00" barrel = 2596.0 fps
    - thus, 1.25" barrel difference ---> 84.5 fps difference = average 67.6 fps increase per 1" barrel

    10mm 135gr tests
    - 6.00" barrel = 1504.0 fps
    - 8.00" barrel = 1575.0 fps
    - 10.00" barrel = 1601.0 fps
    - 12.00" barrel = 1653.0 fps
    - 14.00" barrel = 1691.0 fps
    - 16.00" barrel = 1701.0 fps
    - thus, 10.00" barrel difference ---> 197.0 fps difference = average 19.7 fps increase per 1" barrel

    We know that the 10mm 60gr out of a 6.00" barrel gets us to 2596.0 fps. So let's be very conservative and say that adding 10" barrel will only get us an additional 197.0 fps difference. So, we estimate that the 10mm 60gr out of a 16.00" barrel = 2793 fps.
    Last edited by butlers; 03-22-19 at 14:26.
    "The nation that will insist on drawing a broad line of demarcation between the fighting man and the thinking man is liable to find its fighting done by fools and its thinking done by cowards."
    William Francis Butler

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