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Bullet weights?

Discussion in 'Handguns: General Discussion' started by Smokepole14, Dec 8, 2019.

  1. Smokepole14

    Smokepole14 Member

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    I was playing around with my scale a few days ago and found myself weighing random objects (usually when I’m bored) I found that a paper clip weighs 15gr so it got me to thinking how much does bullet weight matter? From 115gr to 124gr is just 9. The paper clip almost doubled the difference between the two popular 9mm bullets. Do you think that small 9gr can actually cause a bullet to penetrate deeper? Just curious as to what y’all think? Maybe I just have cabin fever lol
     
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  2. drband

    drband Member

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    My uneducated guess is no. But the weight will affect choice of powder charge, resulting velocity, and POI vs POA.

    If loaded to max charge for weight, the lighter bullet will have a lower (I think) POI than the heavier bullet. The lighter bullet may or may not have deeper penetration... I would think it is more dependent on velocity than that slight difference in weight.

    Maybe look up some online ballistic gel tests with different weight bullets?
     
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  3. QED

    QED Member

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    Yes, it's simple physics; a 7.8% heavier bullet will penetrate close to 7% more in gel, assuming all other relevant variables are the same.
     
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  4. pblanc

    pblanc Member

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    Heavier projectiles in a given caliber often carry more momentum than lighter ones. Consider the recent trend to move to the heavy for caliber 147 grain projectile in 9 mm. The 147 grain projectile is slower and gives up a very little kinetic energy to the lighter and faster 124 grain and 115 grain projectiles, but it has about 5% more momentum than 124 grain and more than 9% more than 115 grain.

    Projectiles with greater momentum are more likely to remain on course when striking denser media.
     
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  5. murf

    murf Member

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    percentage-wise (7.8%) those weights are the same difference as between a 165 and 180 grain bullet. yes, the heavier bullet will penetrate deeper (assuming the same profile) due to the greater sectional density of the heavier bullet.

    murf
     
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  6. 460Shooter

    460Shooter Member

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    Testing on this has occurred in various media for a long time. The evidence, ignoring the technical jargon and math, indicates heavier bullets penetrate deeper, and tend to hit a little higher than lighter bullets. Slower velocities caused by shooting heavier bullets can affect expansion from short barrels, but modern bullet designs seem to have largely mitigated that concerns.

    Whether or not a little extra penetration, depending on application, is relevant or meaningful is up to the end user.

    I tend to pick the bullet weight that my gun shoots to POA with fixed sights. Based on that I tend to tweak my adjustable sight guns to shoot the same bullet weights accurately.

    That being said, if I want better penetration for dealing with a big critter, I take the advice of our big game hunters. I choose a heavier bullet, or one of monolithic construction, as they tend to penetrate very deeply.

    9mm=124 gr
    38 Super=124 gr
    38 Special/357 mag=158 gr
    10mm=180 gr
    45acp=230 gr
     
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  7. tipoc

    tipoc Member

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    If we have two bullets both traveling at 1250 fps the heavier bullet will have an advantage in energy.

    So 115 grs. at 1250 fps has 399 ft pds of energy.

    A 124 gr bullet at 1250 fps will have 430 ft pds of energy.

    Not a great deal but as ft pds of energy is a measurement of the bullets ability to do work (penetrate, expand, etc.) and each ft pound increases the ability to do that work...well that's a edge to the bullet.

    That will change if the lighter bullet is faster. But the heavier bullet won't loose the advantage in momentum.
     
  8. 481

    481 Member

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    You're right. For the sake of argument, two hypothetical 9mm FMJs at 1,250 fps weighing 115 and 124 grains according to the MacPherson and Schwartz bullet penetration equations, the 115-grain FMJ would penetrate to 27.7" (Schwartz) — 29.7" (MacPherson) while the 124-grain FMJ would penetrate to 29.9" (Schwartz) — 32.0" (MacPherson). The 'edge' might appear to be slight, but it is there.
     
  9. 35 Whelen

    35 Whelen Member

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    Yes, diameter and construction the same, heavier bullets penetrate more deeply. I bet YouTube is full of videos that will illustrate this.

    These threads are intriguing to me. Coming from a hunting and handloading background, one of the first things I learned is all things equal, excluding velocity, the higher the sectional density, the deeper a bullet will penetrate. I excluded velocity because bullet construction equal, a slow, heavy bullet of a given caliber will out-penetrate a lighter faster bullet of the same caliber. That's why elephant hunters use bullets of high sectional density. That's why the bullet that will drop a whitetail in its tracks wouldn't penetrate enough on large game such as elk and moose. Hunters figured the whole sectional density thing out with the transition from round balls to elongated bullets in the 1800's.

    I hate to delve into the whole "bullet energy" debate again, but where bullet performance is concerned, it tells you exactly nothing. If it was truly indicative of a bullets ability to do work, the a 124 gr. FMJRN at 1150 fps would behave exactly the same as a 124 gr. HP at 1150, but we know that isn't so.

    I've killed a handful of medium game with .357's, a .44 Special and a .45 Colt. In any case of an animal I killed, without calculating it, I couldn't begin to tell you how much energy the bullet had when it hit the animal. It didn't matter as a properly selected bullet at a reasonable velocity was all that mattered.

    Likewise I've killed five bull elk and in any case couldn't begin to tell you any of the bullets energy when they struck. What I do know is how to select the proper bullet with enough sectional density, and the velocity window in which these bullets will expand.

    35W
     
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  10. tipoc

    tipoc Member

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    Here you tend to look past the obvious. The energy figures are independent of and not dependent on a bullets construction. They do not pretend to tell you how a bullet will work. They simply tell you how many ft pounds of energy are available for the bullet to work with and can tell you this for specific distances. Questions of a bullets construction or sectional density are independent factors to look at. Yet they are related to evaluating a bullets overall potential for performance. You are incorrect to think that any of these factors "tell you exactly nothing". Each one sheds light on aspects of potential performance.

    In the example you cite you use two different types of bullets each with different tasks. Yet both being of the same weight and velocity will have the same energy available to each. The construction of the bullets then lets you know that one will tend to expand more and use more energy in doing that while the other will use that same energy in penetration (if shot into similar medium).

    With handgun bullets at typical handgun distances some factors are less important than others.
     
    Last edited: Dec 9, 2019
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  11. 35 Whelen

    35 Whelen Member

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    I knew better....

    Maybe this will help you-

    BULLET “ENERGY” (ft-lbs) VERSUS “TKO” EFFECTIVENESS ON BIG GAME

    35W
     
  12. bassjam

    bassjam Member

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    Consider that the little .177 airgun pellet might only weigh 8-10 grains and a .22 cal airgun pellet weighs roughly the same as your paperclip at 14-20 grains. There have been human deaths associated with airguns in both calibers, and I'm sure many among us have dispatched our share of rodents with a Crossman or Daisy airgun. If they have enough mass on their own to inflict damage, adding that much more to a heavier bullet, keeping velocity the same, will certainly increase its ability to penetrate.
     
  13. QED

    QED Member

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    Momentum would be the same if a bullet mass is increased by 7.8% (in this example) or velocity is increased by 7.8%; both velocity (speed actually) and mass contribute equally to momentum.
     
    Last edited: Dec 9, 2019
  14. ApacheCoTodd

    ApacheCoTodd Member

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    Considering that you've coincidentally picked one of the most common fail/success combos in semi automatic firearms functioning.... I'd have to say that with the significant potential failure of the 115 at the front end of firing (Relax, only in some cases) a flawed performance at the back end is almost a physiological and philosophical foregone-conclusion.

    Or - mayhap I oughta maybe curtail my evening caffeine consumption.;)

    Note: No paperclips were harmed in the formation of this meandering thought.


    Todd.
     
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  15. BarryHalls

    BarryHalls Member

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    Beat me to it. Well said.
     
  16. Walt Sherrill

    Walt Sherrill Member

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    Maybe I'm misunderstanding your comment, and but if so, my apologies. As I understand it, if the lighter bullet is moving faster (and if both the light and heavy bullet are loaded in rounds to their max charge) the faster bullet -- which will typically be the lighter bullet will have dropped less than the heavier bullet. Velocity is the most important factor. Gravity has the same effect on bullets regardless of their weight, so the bullet that get to a given point faster will have dropped less than one that gets their less quickly. If the heavy and light bullets are traveling at the same velocity, they'll impact at the same height.
     
  17. Dibbs

    Dibbs Member

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    It's a two edged sword. Lower mass sheds velocity faster. So, at longer distances the lighter bullet will perform more poorly.
    At shorter distances, that same lighter bullet is faster, with a flatter trajectory.
     
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  18. pblanc

    pblanc Member

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    Over the ranges at which handguns are most commonly shot, the difference in bullet drop due to gravity resulting from differences in projectile speed will be pretty minimal. On the other hand, projectiles that get out of the barrel significantly faster will shoot to a lower POI than slower ones, even within 25 yards. The difference varies a bit with the particular handgun and barrel length.

    The reason is that upon ignition, there is an immediate retrograde force applied to the breech block that initiates muzzle rise during recoil. Even a tiny angular difference in muzzle rise will result in a significant shift in POI.

    Take as an example a SIG P229 chambered in 40 S&W versus 357 SIG. The 357 SIG clears the barrel sooner resulting in a lower POI than the exact same pistol shooting 40 S&W. That is why SIG Sauer puts a shorter front sight on the 357 SIG P229 than it does on the 40 S&W.

    The biggest difference in POI due to projectile mass I ever saw was with a Kahr 9 mm pistol I was thinking of buying used. I shot this pistol with both 115 grain and 124 grain FMJ ammunition. The POI for the 115 grain was close to an inch lower even at a range as short as 15 yards. Both ammunition varieties grouped well. I repeated this experiment with several magazines of each ammunition and the results were consistent.
     
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  19. QED

    QED Member

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    At shorter distances, flatter trajectory is not a significant issue; for given bullet kinetic energy or momentum, short distance or long, the heavier bullet will penetrate more (all else being equal).
     
  20. jmr40

    jmr40 Member

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    Bullet weight alone doesn't determine penetration. The weight of the bullet in relation to diameter is what determines penetration. Heavier bullets in the same caliber are longer and will always penetrate more. It gets complicated when comparing bullets of different calibers but there is a mathematical measurement called sectional density. The higher the SD the more penetration assuming all other factors are the same. That is why a 147 gr 9mm bullet will slightly out penetrate a 230 gr 45 caliber bullet.

    Momentum is a good way to predict how well bullets knock down steel plates and bowling pins when playing shooting games. If I'm ever attacked by hordes of bowling pins or steel plates that is good to know. But it has absolutely nothing to do with predicting how a bullet performs inside living flesh.
     
  21. QED

    QED Member

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    The difference in sectional density in your example is minimal; what is not minimal is typical difference in velocity between 9mm/147 gr. and .45/230 gr. bullets. Sectional density and all else being equal, a bullet with greater velocity penetrates more, hence, in this example, 9mm 147 gr. would typically penetrate more than .45 230 gr. bullet.
     
  22. .308 Norma

    .308 Norma Member

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    Yeppers, that's the way I've always seen it. Way back when, I did some experimenting with a 10.5" Ruger Super Blackhawk 44 Magnum. At 25 yards, it was absolutely amazing to see how much higher the POI was when shooting 250gr bullets at 1,000fps, compared to shooting 200gr bullets at around 1,500fps.
    I know a 10.5" barreled 44 Magnum is probably an extreme example. But I seen the same thing when shooting factory 158gr, 38 Special ammo in a 4" 357 Mag revolver that was sighted to hit dead on at 25 yards with factory 125gr, 357 Mag ammo. From the bench, I could keep all of the 38 Special bullets in a nice 3-4" group, but the group was about 8" above the bullseye!
    Just as another example - if your 44 Magnum is loaded with those swagged lead, 240gr SWCs at 800-900fps, and you want to use it to snip the head off a "Fool Hen" forest grouse at 15ft, you need to aim at the base of the Fool Hen's neck. If you aim right at bird's head, you'll probably shoot over it, and the Fool Hen might fly away.;)
     
  23. tipoc

    tipoc Member

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    I've read this before. I'm not surprised that you can't see the weaknesses of the argument.

    "Many decades ago, some gun writers started comparing cartridge effectiveness by measuring and applying the cartridges ft-lbs (Kinetic) of energy. That trend of using ft-lbs to calculate “killing power” has become pervasive, industry-wide." That's not exactly true but leave that for another time.Rather than state and explain (as I have done many times) that the idea of ft. pds. of energy being misplaced for "killing power" is an error and then explaining what it's role actually is, they make a mistake or arguing against a straw man. The origins of the concept of kinetic energy does back to the Greeks. The formulas were designed to described things in nature. They were not developed to determine what bullet is best at killing something. The essay at Buffalo Bore argues as if the formula was developed for that purpose.

    Energy is only one piece of selecting a bullet matched to the task a shooter wants to complete. It goes hand in hand with momentum, bullet construction and at appropriate distances sectional density (the latter not playing much of a role at typical handgun distance.)
     
    Last edited: Dec 11, 2019
  24. TikkaShooter

    TikkaShooter Member

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    X2!!! I pick the load, bullet, primer and OAL etc my firearm prefers. I've learned to accept I can't convince any firearm to accept what I think over what it prefers.
     
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  25. Walt Sherrill

    Walt Sherrill Member

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    With semi-autos that have a fixed barrel (like most of the .380s, 32s, 25s, and .22s) and revolvers, when the bullet is fired, recoil begins to be transferred immediately to the frame. That rearward movement, which is above the shooter's hand, causes barrel rise (which is directly attached to the frame and the grip in the shooter's hand) causes the whole assembly to rock back in the shooter's hand. The barrel doesn't rise until its rearward movement hits a stop (in the case of the gun, the barrel is attached to the top of a long handle (the grip).

    Guns using the Browning Short Recoil Locked Breech design (which includes nearly all other center-fire handguns) handle recoil differently than fixed barrel semi-autos or revolvers.

    The initial force of the recoil pushes the slide and barrel to rear -- and the bullet typically leaves the barrel before the barrel and slide have moved more than 1/10th of an inch to the rear. While ecoil force will be transferred to the frame throughout the barrel/slide movement to the rear, only a small amount of recoil can be transferred to the frame during that 1/10th of an inch of slide/barrel travel (before the bullet leaves the barrel.) ​

    The barrel won't begin to rise until the barrel and slide hit their respective stops on the frame. Then the remaining substantial recoil force will cause the gun to rock back in the shooter's hand. With the Browniing SRLB design, the same recoil force is transferred to the frame as with other designs, but the initial transfer of the recoil is delayed -- generally until after the bullet is gone.

    If you doubt this, watch any number of ultra-high-speed videos of Brownign SRLB guns being fired on YouTube. There will be almost no barrel rise visible or measurable until AFTER the bullet is gone. At most handgun distances (maybe up to 50 yards, the biggest difference in pointsof impact will be due to velocity and gravity, not to round-induced barrel rise.
     
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