POI for same bullet gr weight, but different velocity?

This is a discussion on POI for same bullet gr weight, but different velocity? within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; Greetings brothers/sisters-in-arms! OK, here's a question for ya.... I'll soon be taking possession of a Sig P220 (45ACP of course!) and will need to polish ...

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Thread: POI for same bullet gr weight, but different velocity?

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    Member Array JusAguy's Avatar
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    Question POI for same bullet gr weight, but different velocity?

    Greetings brothers/sisters-in-arms!

    OK, here's a question for ya....

    I'll soon be taking possession of a Sig P220 (45ACP of course!) and will need to polish up my tarnished handgun shooting skills.

    I plan on using 230gr JHP's for home-defense/carry so it makes sense to me to use the same bullets for training. However, the home/self-defense rounds are EXPENSIVE!!! I don't have a big budget for training so I'll need to use cheaper 230gr FMJs for practice.

    With handguns there is so much volume (though I believe in quality training vs quantity "spray and pray") that training can become quite expensive...

    Given that I'll restrict my training to 25yds max, will I experience a *noticeable* difference in POI from the (likely) hotter velocity 230gr JHP's in these shorter distances?

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    I do most of my shooting at 15 yards, and I see no significant difference in POI between factory SD loads in 230 grains and my milder 230 grain LRN reloads. Your POI may vary, of course.
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    I've seen on other forums where slower bullets tend to land higher due to the longer amount of time spent in the barrel.
    Recoil begins as soon as the bullet starts to move. A slower bullet leaves after the barrel has started to tip back.
    How much depends on grip, weapon weight, and difference in velocity. Switching between two 230 grain rounds, your only difference should be speed.
    Take some notes. Slow, deliberate aimed fire (FMJ & JHP)
    Please report back!
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    Quote Originally Posted by hdhnict View Post
    I've seen on other forums where slower bullets tend to land higher due to the longer amount of time spent in the barrel.
    Recoil begins as soon as the bullet starts to move. A slower bullet leaves after the barrel has started to tip back.
    How much depends on grip, weapon weight, and difference in velocity. Switching between two 230 grain rounds, your only difference should be speed.
    Take some notes. Slow, deliberate aimed fire (FMJ & JHP)
    Please report back!
    Yeah, I'm sure I'll have to do some direct comparison shooting (both supported and "unsupported"). Unfortunately the SD stuff is prohibitively expensive to establish (all by myself) a substantive body of data that provides reliable, predictable information.

    I suppose I could take published velocities from the respective rounds/manufacturers and plug 'em into a ballistics calculator to establish simple, theoretical trajectory changes. However, simple mathematical trajectory isn't the entire ballistic "picture".....

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    Distinguished Member Array dangerranger's Avatar
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    With some careful tuning of hand loads I can get the point of impact of my practice ammo to match my carry stuff. But only at certain distances. Beyond 30 yards my practice stuff tends to fall much more quickly. But at 7, 10, and 15, yds not much difference. DR
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    There is no reason to believe a "self defense" round will have any more velocity than a FMJ. The brand would matter more, or +P vs. standard pressure.

    Some people get all tied up debating carrying one weight bullet but training with a different weight. POI change is often smaller than the pistol (or individual!) can group. There is zero reason to practice with your high dollar defensive ammo. Ensure it reliably cycles the pistol it will be used in, and train with cheap range ammo.
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    I may be wrong here....


    But I thought that if you we're to drop a bullet at the same time you fire the bullet from your gun, both bullets will hit the ground at the same time.

    The two (2) bullets needs to have the same weight "mass"
    The bullet fired from the gun needs to be fired exactly level.
    Both the bullet being dropped and fired from the gun needs to happen at the same exact time.

    This being said I don't think that they should be too different when they hit your target.

    The above statement does not take into account the velocity / recoil relationship while the bullet is in your weapon.

    Please let me know if I'm wrong.

    My best advice would be to shoot 25 to 50 rounds of each at the same distance on the same range trip.
    If they are realitivly close just use the FMJ's.

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    If you are good enough to really notice the difference at 15 yards.....ya don't need the practice!
    Ignorance is a long way from stupid, but left unchecked, can get there real fast.

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    If you're using the Winchester white box or Remington's UMC ammo, the groups you'll shoot will be large enough to mask any difference in POI relative to the high-priced spread. Shooting my 200 gr SWC reloads right next to a 'generic ball' group was extremely gratifying - the reloads cutting the group size about in half. The good defensive ammo will probably shoot even better.
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    Distinguished Member Array Nmuskier's Avatar
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    Quote Originally Posted by JeepCreeper View Post
    I may be wrong here....


    But I thought that if you we're to drop a bullet at the same time you fire the bullet from your gun, both bullets will hit the ground at the same time.

    The two (2) bullets needs to have the same weight "mass"
    The bullet fired from the gun needs to be fired exactly level.
    Both the bullet being dropped and fired from the gun needs to happen at the same exact time.
    For this experiment, bullet mass does not matter. The fired projectile does need to be level. The bullet leaving the muzzle begins to accelerate downward (fall) independently of its forward vector.

    The difference in bullet POI from different rounds is (at longer ranges, and typically in rifles) is because lighter rounds, with the same powder load, have a faster MV. This gets them to the target faster, thus falling for less time. Objects that fall for less time fall less distance (higher POI).

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    VIP Member Array ccw9mm's Avatar
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    Quote Originally Posted by JusAguy View Post
    POI for same bullet gr weight, but different velocity?
    On a Ransom Rest, I suppose one could find detectable differences. And I'm sure many can feel like there are some differences between certain cartridges.

    Generally speaking, though, I've shot so many different rounds that I tend to rapidly adjust to the new round. I no longer know what minor adjustments I've made; I just make them. And so, POI doesn't seem to vary much. In much smaller, lighter, shorter guns it seems to be more visible, the differences, though these days in most guns I'm no longer able to see much difference.

    Data point: In hotter, higher-pressure +P type loads in a Browning BDM 9mm, back when, I noticed that POI was a bit higher at given distances, as compared to more-sedate "range" rounds. But after tens of thousands of shots through the gun, a few shots is all it took to make whatever adjustments in the firmness and positioning of my stance and grip to accommodate. These same minor changes in basic technique are what I do these days. Doesn't take but a few rounds to make the adjustment. The way I think of it, it's similar to how swinging a 28oz vs 32oz baseball bat is done. Same swing, more or less, but the grip, "firmness" and speed changes occur naturally as we swing. An experienced batman can make these minor changes without thinking, and without much change in the "POI" of the ball (cartridge).
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    I know you mentioned cost a few times.
    I just checked on ammoseek and practice rounds (Tula and Blazer non reman) were at $.30/round
    The SD rounds like Speer Lawman and Federal (HP) were averaging $.45/round

    So, not counting shipping costs (which vary based on quantity bought - I just bought 1000 rnds and shipping was $19.95). You can spend $75 worth of 100 rounds of each and get a pretty good picture how the different ammo acts with your personal dynamics.
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    I know most folks here are more expert than me about this stuff. But, it seems to me if your target looks more like a 6" x 6" piece of Swiss Cheese than a single 1" hole it really can't make that much difference.

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    Quote Originally Posted by StevePVB View Post
    I know most folks here are more expert than me about this stuff. But, it seems to me if your target looks more like a 6" x 6" piece of Swiss Cheese than a single 1" hole it really can't make that much difference.
    Given the location, know. But a 1" hole that misses all major parts could do more bad than good. Swiss cheese over the heart and lings will go a long way to stopping a BG. Likewise, a 1" hole through the heart will also stop the BG.

    Accuracy and location mean alot
    Nehemiah 4:14: “Don’t be afraid of them. Remember the Lord who is great and awesome, and draw your Beretta PX4 and fight for your brothers, your sons and your daughters, your wives and your homes.” highlighted added by LMP

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