Heavier Bullets Striking Higher or Lower


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KodiakBeer
December 1, 2010, 08:51 PM
I'll assume you're shooting standard 230 grain ball? Lighter rounds (165, 185) will usually shoot lower than 230, but I wouldn't expect them to impact 5" low!

The cheapest first step you can try is replacing the barrel bushing with a standard Colt (whatever), bushing. It may be that the bushing is out of spec. Maybe just borrow one from a friend and try it.

If that doesn't work you'll just have to replace the front sight with a lower one. That can be a pain in the rear if you do it yourself because you'll have to figure out the dovetail size, etc.

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Cards81fan
December 1, 2010, 10:08 PM
I'll assume you're shooting standard 230 grain ball? Lighter rounds (165, 185) will usually shoot lower than 230, but I wouldn't expect them to impact 5" low!


I believe lighter bullets generally have less drop, as they have a higher velocity and will reach a given distance quicker than a heavier, slower projectile. The bullet drops less in that shorter time interval than the larger bullet that takes longer to get there.

KodiakBeer
December 1, 2010, 10:21 PM
I believe lighter bullets generally have less drop, as they have a higher velocity and will reach a given distance quicker than a heavier, slower projectile.

You're mistaken.

MidwestRookie
December 1, 2010, 10:36 PM
such an awesome rebuttal...can you at least say why in a sentence or something? I'd like to know how a heavier projectile will drop less..

147 Grain
December 1, 2010, 10:48 PM
Lighter bullets at higher velocity spend less time in the barrel. Heavier bullets are slower and spend more time in a barrel that's recoiling upwards for a higher POI than lighter loads.

Clifford
December 1, 2010, 10:57 PM
147 grain is correct a heavier projectile will shoot higher then a lighter bullet.

Cemetery21
December 1, 2010, 11:35 PM
Cards81 is right on the trajectory, but it doesn't take into account the recoil induced deflection, which 147 explained. The heavier bullet leaves the barrel at a steeper angle (in "normal" loads).

I also agree that initial sight testing should be done from a rest. Also, have your buddy put a dummy round somewhere in your magazine. You will see if you have a flinch to work on.

Cards81fan
December 1, 2010, 11:36 PM
Apparently Speer and I are on one side of this argument, and everyone else is on the other:

:scrutiny:

http://www.speer-ammo.com/ballistics/ammo.aspx

A .357 125gr drops 5.2" at 100 yards. Their 158gr drops over 7".

A heavy bullet leaves the barrel at whatever angle I am aiming it at. Recoil doesn't affect where the gun shoots if I am handling the firearm correctly; it hits at my point of aim. Plus, all bullets drop at the same rate due to gravity. That is simply physics. But of they take longer (due to a slower velocity) to reach the target, they they will have dropped further.

You all can believe what you like. I am going to trust Speer's published information and the physics of gravity on the matter.

Clifford
December 1, 2010, 11:52 PM
Speer's testing was done in a barrel fixture. Not in a persons hand. Barrel transit recoil is very real.

I'm not trying to be an *********, it is what it is. Yes over any given range any round moving slower will drop more than a faster round at the same range. Proper grip is important but NO human can grip a pistol hard enough to keep it completly immobile during recoil. The heavier bullet simply takes more time to exit the barrel and during that time the barrel will rotate up farther than it would with a lighter projectile.

Don't belive me? Look at the line of sight in relation to the bore on a revolver. The barrel points lower than the sights do...they don't make them like that cause it looks cool.

Cemetery21
December 1, 2010, 11:59 PM
My apologies to Cards81fan. I cited the wrong member in my original post. I edited it to correct that.
Speer and Cards81fan are correct that lighter, faster bullets fly flatter. But they are usually launched at a lower angle than heavier, slower bullets from the same gun.

KodiakBeer
December 2, 2010, 01:41 AM
Apparently Speer and I are on one side of this argument, and everyone else is on the other:

All nonsense aside, simply shoot your .45acp with 230 grain and 165 grain slugs, or your 9mm with 115 grain and 147 grain slugs (or any handgun with the heaviest and lightest standard loads) at 25 yards or so. The heavy slugs will hit the target higher than the lighter slugs, in every case.

Several people have explained why this happens, but it's hardly worth arguing about it. Just go to the range and see for yourself.


.

BCRider
December 2, 2010, 05:04 PM
Apparently Speer and I are on one side of this argument, and everyone else is on the other:

A .357 125gr drops 5.2" at 100 yards. Their 158gr drops over 7".


First off we seldom shoot handguns out to 100 yards. In close at ranges of less than 25 yards the internal ballistics of the time in the barrel and the rise due to the recoil before the bullet exits are the dominant effects that cause lighter bullets to impact low and heavier bullets to hit high. At some medium range this recoil induced rise and the bullet drop would cancel and by the time you get to Speer's 100 yards range the bullet drop from gravity would be the more meaningful factor. So you're right and we're right. It just depends on the distance being considered.


A heavy bullet leaves the barrel at whatever angle I am aiming it at. Recoil doesn't affect where the gun shoots if I am handling the firearm correctly.......


Just for fun you may want to try sticking a cleaning rod and bore brush with a centering bushing down the barrel and see what angle there is between the top of the sights and the bore axis line up. I think you'll be surprised to see that the bore is actually angled downwards compared to the sight line. All defense style handguns seem to be set up for around 20 to 25 yards. At that distance there's signifcant barrel rise from recoil before the bullet leaves the barrel. This is why heavy bullets tend to hit higher than lighter and faster bullets AT CLOSE RANGE.

Meanwhile, back at the original question....

Holo, did you buy the gun NEW with these sights? Or is it possible that a previous owner has changed them but mistakenly used front and rear sights that are not a height match to each other?

Magnumite
December 2, 2010, 05:14 PM
Kodiak is right. When using the same sight setting, lighter bullets strike lower. Take up magnum revolver shooting for enhanced experience in this phenomenon.

Bullet drop and point of impact are not the same thing when considering two bullet weights and one sight setting. You can only directly compare bullet drops when using the same zeros. And an adjustment needs to be made when changing bullet weights.

9mmepiphany
December 2, 2010, 08:49 PM
Apparently Speer and I are on one side of this argument, and everyone else is on the other:

A .357 125gr drops 5.2" at 100 yards. Their 158gr drops over 7".
Lighter bullets at higher velocity spend less time in the barrel. Heavier bullets are slower and spend more time in a barrel that's recoiling upwards for a higher POI than lighter loads.
The heavy slugs will hit the target higher than the lighter slugs

The interesting point is that these are all correct and not really arguing different sides, just different perspectives of the same point of Physics.

Cards81fan is correct about where a heavier bullet will strike a target at 100 yards. 147 Grain and KodiakBeer are correct concerning the bullet strike at the distance stated in the OP

The trajectory of a bullet when it leaves the barrel of a handgun...actually any gun...describes a parabola that will intersect points along the line of sight twice. Once while the bullet is rising and again when it is descending...147 Grain and KodiakBeer are referring to a point closer to the former, Cards81fan, and the Speer manual, are looking at a point closer to the latter.

At 7-10 yards the heavier bullet is still rising above the pre-ignition point of sight and will hit higher than a lighter bullet which has left the barrel later in the arc of the muzzle flip. At 100 yards the heavier bullet has passed the mid-point of it's arc and is falling more quickly, in response to gravity, than the lighter bullet and will strike a target lower

9mmepiphany
December 2, 2010, 09:02 PM
Rather than clutter up the other thread, http://www.thehighroad.org/showthread.php?t=558126, I've given this a home of it's own.

There are several interesting teaching points here

If you'd like some information I've move posted into the original thread, please repost it over there

M1key
December 3, 2010, 12:09 AM
Generally, for me, heavier bullets tend to shoot higher, above POI than lighter bullets...out of pistols.


M

GLOOB
December 3, 2010, 02:10 AM
I've also noticed this effect with changes in powder charge. In my revolver, 158 grain full magnum loads hit right around the POA. When I shoot my powder puff 148 grain wadcutter loads, the POI at short ranges is noticeably higher - about 1-minute-of-Coke-can at 30-40 feet. I assume it's because the bullet is in the barrel longer.

BCRider
December 3, 2010, 03:51 AM
Gloob, that's what I found as well. But in my case my 19 is sighted for .38spl so the magnums hit low.

I often play around by chambering one magnum and five .38's. Sort of Revolver Roulette :D The five .38's all print in about a 1.5'ish inch group at 12 yards unless I get a bit lucky and the magnum is consistently a good 3 inches low of the group.

I was puzzled at this as well until a long time shooter explained what was going on.

wanderinwalker
December 3, 2010, 07:00 PM
I've also noticed this effect with changes in powder charge. In my revolver, 158 grain full magnum loads hit right around the POA. When I shoot my powder puff 148 grain wadcutter loads, the POI at short ranges is noticeably higher - about 1-minute-of-Coke-can at 30-40 feet. I assume it's because the bullet is in the barrel longer.

Yep, exactly.

As I posted in the thread on the revolver forum, consider that the amount of movement required to change the point of impact down range is very slight. We've all seen the high speed footage that "proves" the bullet leaves the barrel "before" the gun recoils. Well, no, it doesn't. What the high speed shows us is that the bullet has exited the barrel before the MAJORITY of the felt recoil occurs. The pistol is moving in reaction to the bullet traveling down the barrel from the moment of ignition, Newton's Third Law in action.

Here is the formula to figure out sight corrections based on error:

Distance on target * Sight Radius/ Range to Target = Correction

So if you figure a bullet hits 2" low at 25 yards on a pistol with a 6" sight radius, the movement to create that 2" difference is:

2 * 6 / 900 = .013"

Measure that amount. It's not a very big movement. Now think that if one load shoots 2" higher than another at 25 yards in a handgun, it's that much difference in where the muzzle is when the bullet exits.

Now if my math and idea is completely wrong, I hope somebody can point out where I went wrong, because this makes sense to me.

o Unforgiven o
December 4, 2010, 01:29 PM
If somebody made a post here that they can't shoot more than a dinner plate size group at 5 yards with their (insert firearm here), I have no doubt that their would be a small army of people that would say that the (insert firearm here) is much more accurate than that and the shooter is to blame for the accuracy problems.

What you guys are saying about bullet drop is akin to saying that the accuracy problems are correct because the (insert firearm here) is in the shooters hand when he fires it because the only way for both to be true they have to be affected by a shooter.

So if you put the gun in a vise, the heavier bullets would no doubt drop more than lighter bullets and the (insert firearm here) would be much more acurate than so and so is able to shoot it , but that's "not true" because of shooter induced variables.

So why does one need a vise to be true and the other has to held to be true? That is the point I am trying to make, that if you were to remove the shooter from the equation the "bullet drop" and "terrible accuracy" claims are both incorrect.

Balrog
December 4, 2010, 03:17 PM
So much misinformation in this thread...

The Speer data is not relevant to shooting offhand at 25 yrds. When reloading companies calculate velocity and trajectory, they do so from a test barrel that is locked into position and does not move with firing.

Heavier bullets will impact higher, when you are shooting offhand at 25 yds.

buck460XVR
December 4, 2010, 03:40 PM
So much misinformation in this thread...




I don't think it is so much misinformation as it is confusion. Folks are confusing trajectory with POA/POI.

Walkalong
December 4, 2010, 05:01 PM
I don't think it is so much misinformation as it is confusion. Folks are confusing trajectory with POA/POI.Yep.

Lighter bullets at higher velocity hit lower than heavier bullets at lower velocity at close range due to reduced time in the barrel and recoil.

At some point in time/distance along the trajectory, the heavier ones will fall below the lighter ones due to the differences in trajectories.

GLOOB
December 5, 2010, 01:24 AM
You know, I'm thinking that the change in POI should be much greater in a revolver compared to a typical locked breech semi-auto. The mass of the recoiling slide and barrel would tend to delay some of the upwards movement. Whereas in a revolver, the mass in the cylinder and the high bore axis cause the gun to rotate, immediately.

ironhead7544
December 5, 2010, 11:11 AM
Theres no hard and fast rules on this. To many variables. I have seen both with different rifles/pistols/sights/distances. You will need to test the actual firearm and loads. The trajectory tables are close but you can not assume they will be exact unless you do a test with the actual gun.

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