Bullet weight differences in POI

[RobS]

I am presenting two questions that has intrigued interest.

1. Generally speaking, will the POI be higher shooting heavier bullets vs lighter bullets in a revolver assuming velocities are similar? True or False

2. Again generally speaking, will the POI be lower shooting heavier bullets vs lighter bullets in a rifle? True or False

[captaint]

Rob,
POI will be higher with heavier boolits. Lower with lighter boolits, assuming same velocity. The reason is barrel time. Longer with heavier boolits, shorter with lighter boolits. Enjoy Mike

[Shiloh]

Noticeably with heavier boolits from a handgun.

Shiloh

[Bass Ackward]

Key word in all of this is "generally" which really means statistically. And that is going to be based upon short ranges and common barrel lengths.

If you want to make this real interesting, have both launching platforms with 16" barrels and open sights and then ask the same questions.

[44man]

Not so much barrel time with the same velocity but more recoil effect that will raise the barrel quicker and higher.
Shoot the heavy boolit with a death grip and the lighter one with a more relaxed grip and POI might be close.
I don't know how much gun weight change works on this. I always shoot all 5 shots for groups and I shoot long range a lot. By the time I get to the last shot in my .475, I have lost 4 oz in gun weight. In my .45 Vaquero I lose 3.38 oz and since the gun is lighter to start with, how much does it cause elevation differences?
Now a rifle, I don't know because of the way it pushes straight into the shoulder first. At the higher velocities even spin differences can alter POI. I would not place bets that a heavy bullet will hit higher.

[RobS]

Now a rifle, I don't know because of the way it pushes straight into the shoulder first. At the higher velocities even spin differences can alter POI. I would not place bets that a heavy bullet will hit higher.

My experiences with rifles are the opposite of revolvers.............heavier bullets have a lower POI vs the lighter ones at around the same velocity; that is my rifle experience anyway. Anyone else have thoughts with the rifle vs bullet weight scenario.

Good thread so far..........................

[AZ-Stew]

Try shooting wax boolits from a revolver. Their lower mass results in almost no recoil and FAR lower POI.

Lots of variables in a rifle. Distance, bedding, ballistic coefficient, etc. Generally though, a heavier bullet will have a lower POI at a given distance until the range gets long. Then ballistic coefficient may reverse the trend, with the lighter, lower BC bullet having more drop.

Regards,

Stew

Regards,

Stewe

[fredj338]

Not so much barrel time with the same velocity but more recoil effect that will raise the barrel quicker and higher.
Shoot the heavy boolit with a death grip and the lighter one with a more relaxed grip and POI might be close.
Now a rifle, I don't know because of the way it pushes straight into the shoulder first. At the higher velocities even spin differences can alter POI. I would not place bets that a heavy bullet will hit higher.
exactly my exp. shooting everything from 9mm to heavy 45colt in handguns & 223 to 458lott in rifles.

[BOOM BOOM]

hi,
I have had both pistols & rifles POI be higher w/ h

[jdgabbard]

I disagree with all stated reasons. And I'll give my opinion on why.

First off, as stated many times over, we don't know exactly how internal ballistics work. Everything thing, down to how lube works, is nothing but theory. These are things that we guess at. And because we're able to achieve consistent results with these theories, we arrive at a conclusion.

However, if one refers to physics, we have several things that we've concluded as fact. First of these is force in motion. This is much like when you take a turn in you're car at high speed, you're body (and the car) tend to want to continue in a straight direction. This is magnified with greater mass. A heavier boolit with the same velocity as a lighter one has more mass, and thus a greater energy. Physics says that between these two the heavier boolit should steer a straigher course then the lighter one. As it has more force in motion.

Not only is this one reason why I disagree with the recoil theory, and the muzzle flip, but also the fact that when locked into a rest that allows minimum movement of the firearm the same results are shown. If one of those two were the cause of this, it would show both boolits having a near identical point of impact. These types of tests show differently.

As I said before, this is just my opinion. And as such, is my .02

[yondering]

In handguns:
heavy bullets and/or low velocity = high POI
light bullets and/or high velocity = low POI

Sometimes you can work the loads just right to get a heavy bullet at high velocity to have the same POI as a light bullet at lower velocity. A good example is the 45 Colt, a 255gr @ 1,000 fps will often have a POI very close to a 300gr @ 1,200-1,250 fps. One for target, one for hunting.

Rifles don't have (usually) as severe muzzle flip as handguns, so other factors like bullet drop and barrel harmonics can have more impact.

[yondering]

but also the fact that when locked into a rest that allows minimum movement of the firearm the same results are shown.

What rest are you using that doesn't allow the handgun to move when fired? I'd like to see some test results documenting what you claim.

[44man]

I disagree with all stated reasons. And I'll give my opinion on why.

First off, as stated many times over, we don't know exactly how internal ballistics work. Everything thing, down to how lube works, is nothing but theory. These are things that we guess at. And because we're able to achieve consistent results with these theories, we arrive at a conclusion.

However, if one refers to physics, we have several things that we've concluded as fact. First of these is force in motion. This is much like when you take a turn in you're car at high speed, you're body (and the car) tend to want to continue in a straight direction. This is magnified with greater mass. A heavier boolit with the same velocity as a lighter one has more mass, and thus a greater energy. Physics says that between these two the heavier boolit should steer a straigher course then the lighter one. As it has more force in motion.

Not only is this one reason why I disagree with the recoil theory, and the muzzle flip, but also the fact that when locked into a rest that allows minimum movement of the firearm the same results are shown. If one of those two were the cause of this, it would show both boolits having a near identical point of impact. These types of tests show differently.

As I said before, this is just my opinion. And as such, is my .02
One easy test for you. Shoot a .475 revolver with the same load and boolit. Don't even mess with a light or heavy, just use one.
Shoot a target at 50 yards with both hands then shoot with one hand and show us the target.
I think you will find POI in a revolver is recoil controlled. If you don't hit a lot higher with one hand we will change your avitar to the 800# goooorilla. :bigsmyl2:
Now shoot it from a rest and just try to lock it down, even a tiny change in the bags will ruin a group and you can tell without looking where the boolits are going based on the changes in recoil and torque.
As the caliber gets smaller and recoil is reduced, the difference is very small and that is where boolit weight alone will change recoil and POI.

[jdgabbard]

If you don't hit a lot higher with one hand we will change your avitar to the 800# goooorilla. :bigsmyl2:

LMAO...


What rest are you using that doesn't allow the handgun to move when fired? I'd like to see some test results documenting what you claim.

I havent used one with a handgun, but I have seen them used with a rifle. As for the results, I myself have not performed these tests. However I have read them. I'll see if I can't dig them up for you....

[AZ Pete]

my experience is that heavier bullets have a higher poi. My experience is at 25 yards with revolvers and 100 yards with rifles. :drinks:

[Slow Elk 45/70]

I will add that the powder will enter into this equation, maybe not so much in short BBL, but the faster powders punch the boolit out faster, while the slower powders seem to burn longer in the BBL, so you have more time for the slug in the BBL, while recoil moves the muzzle up and the boolit will strike higher, JMHO...there are a lot of factors that enter into this discussion, most of them mentioned above....IMHO

[geargnasher]

I disagree with all stated reasons. And I'll give my opinion on why.

First off, as stated many times over, we don't know exactly how internal ballistics work. Everything thing, down to how lube works, is nothing but theory. These are things that we guess at. And because we're able to achieve consistent results with these theories, we arrive at a conclusion.

However, if one refers to physics, we have several things that we've concluded as fact. First of these is force in motion. This is much like when you take a turn in you're car at high speed, you're body (and the car) tend to want to continue in a straight direction. This is magnified with greater mass. A heavier boolit with the same velocity as a lighter one has more mass, and thus a greater energy. Physics says that between these two the heavier boolit should steer a straigher course then the lighter one. As it has more force in motion.

Not only is this one reason why I disagree with the recoil theory, and the muzzle flip, but also the fact that when locked into a rest that allows minimum movement of the firearm the same results are shown. If one of those two were the cause of this, it would show both boolits having a near identical point of impact. These types of tests show differently.

As I said before, this is just my opinion. And as such, is my .02

I've got a theory, too, and it's based upon results, just like 44man's. Try shooting any centerfire revolver from bags on a table. First, just rest your wrists in a two-handed grip on the bags and fire a group. Then, rest the butt on a block of wood and support your barrel with bags, same two-handed hold, and shoot another group with the same ammo. 25 yards or so. I'll put money on the butt-on-block hold will shoot 2-5" lower. Don't believe me? Try it. Then I think you'll agree that recoil/barrel time makes the gun shoot higher. How else do you explain a SAA having a front sight 1/4" higher than the groove in the topstrap above bore centerline and yet still shoots high?

A ligher boolit at the same velocity produces less actual recoil, less muzzle flip, therfore lower poi because the muzzle is not pointed as far up when the boolit leaves it. A lighter boolit loaded to the SAME ENERGY as a heavier one (i.e. enough velocity increase to match the force of the heavier load) will likely hit about the same area as the heavier one when fired from a pistol.

In rifles, where muzzle flip is minimal, this is not much of a factor. A bowling ball and a piece of lead shot will hit the ground at the same time, only difference being air resistance. A boolit dropped and a boolit shot are dropping at the same rate, too, only one travels through hundreds of yards of air and one only travels through about one yard of air, so the fired one will stray a bit behind as it has more resistance to encounter.

Boolits fired from the horizontal from a stable platform (no muzzle flip) will all have the same rate of drop, regardless of velocity. The reason poi at a given rangediffers is heavier boolits are usually slower, and have longer to fall before they reach the target. At the same velocity all the way to the target they will hit in the same place as the ligher ones, but usually this isn't observed because the BC is often lower for a heavier boolit. BC matters to poi as does caliber because the boolit cuts the air better/worse and is losing velocity at a lesser/faster rate downrange, thus having more/less time to fall toward the earth.

Not my .02, that's Galileo's and Newton's.

Gear

[Recluse]

My experiences with rifles are the opposite of revolvers.............heavier bullets have a lower POI vs the lighter ones at around the same velocity; that is my rifle experience anyway. Anyone else have thoughts with the rifle vs bullet weight scenario.

Good thread so far..........................

Same here--my heavier rifle boolits hit significantly lower than my lighter jacketed bullets.

But it's not apples to apples, either. My cast boolits are being pushed considerably slower, in most cases, than the lighter jacketed boolits.

Be interesting to see what would happen if I loaded some up to equal velocities, just different weight (and composition) bullets.

:coffee:

[RobS]

Great someone else that has a low POI with heavy bullets in a rifle. For example my Puma 454 Casull will shoot a 280 grain bullet 3-4 inches higher than the 345 grain bullet both traveling at around 1,150 fps at 50 yards.

I was beginning to think that my barrel was bent funny or somthing :)

[44man]

One thing I have not figured out yet. My 320 gr .44 boolit drops around 35" at 200 yards. My 420 gr .475 boolit drops about 18", both are about the same velocity.
Is it the fierce recoil of the .475 or is it because it does not bleed off velocity as fast? There is no way to hold the wrist twisters barrel down.

[armyrat1970]

It seems to me one factor that needs to be taken into consideration is the range that the weapon is fired at, with the given boolit weight. At longer ranges the lighter boolit should drop quicker. A lot of different things add to the equation.

[yondering]

One thing I have not figured out yet. My 320 gr .44 boolit drops around 35" at 200 yards. My 420 gr .475 boolit drops about 18", both are about the same velocity.
Is it the fierce recoil of the .475 or is it because it does not bleed off velocity as fast? There is no way to hold the wrist twisters barrel down.

Now your talking about external ballistics and bullet trajectory, which is a whole different thing, and has nothing to do with recoil or muzzle flip.

If you could figure out the ballistic coefficient of those bullets and plug the data into a ballistics table, you'd have the answer. Without knowing any other details, the sectional density of your .475 bullet is higher, so ballistic coefficient may be higher, which means less drop downrange at the same velocity.

[44man]

Now your talking about external ballistics and bullet trajectory, which is a whole different thing, and has nothing to do with recoil or muzzle flip.

If you could figure out the ballistic coefficient of those bullets and plug the data into a ballistics table, you'd have the answer. Without knowing any other details, the sectional density of your .475 bullet is higher, so ballistic coefficient may be higher, which means less drop downrange at the same velocity.
Yes, you are right but since I don't change my sight setting for 75 yards, it is hard to match them. Sight settings are made to take into account barrel rise, how the gun is gripped, etc. It is not easy to compare two different calibers at long range. I could only compare two different boolits from the same gun with actual 200 yard sight settings.
So my drop over the distance might be affected by different barrel rise and recoil which is giving me a higher mid range trajectory from the .475. Of course if I sighted the .44 and .475 at 200, I would have zero drop. Then I would have to know the mid range to see which carries better.
The only other way is to shoot at a 50 yard target set so the boolit also hits the 200 yard target. That would be a good way to separate caliber drop.

[yondering]

Yes, you are right but since I don't change my sight setting for 75 yards, it is hard to match them. Sight settings are made to take into account barrel rise, how the gun is gripped, etc. It is not easy to compare two different calibers at long range. I could only compare two different boolits from the same gun with actual 200 yard sight settings.
So my drop over the distance might be affected by different barrel rise and recoil which is giving me a higher mid range trajectory from the .475. Of course if I sighted the .44 and .475 at 200, I would have zero drop. Then I would have to know the mid range to see which carries better.
The only other way is to shoot at a 50 yard target set so the boolit also hits the 200 yard target. That would be a good way to separate caliber drop.

If they're both zero'ed at 75 yards, then you're just seeing the trajectory difference between the two rounds. Recoil is not part of this.

If you give me the velocity of each round, the height of your scope or sights above the barrel, zero range (75 yards?), and the exact drop at 200 yards, I'll plug the info into my ballistic table and be able to tell you an approximate ballistic coefficient and trajectory for each. Shoot me a PM if you want.

[armyrat1970]

The given time the boolit leaves the muzzle upon firing is so quick that I don't feel recoil or barrel rise has any effect. I know one thing. When I have my sights on target, and I squeeze the trigger as I should and the fired shot surprises me, I have a good shot on target. No matter the recoil or barrel rise.

[Butcher45]

My .45 air rifle was zero'd while shot from a seated position for 143grain roundball before shooting the groups in the hollowpoint testing post from the prone position. The 230, and 245grain prone position groups hit lower than 143grain roundball zero'd at 50 yards from a seated position. Air recoil is a bit slow.

[fredj338]

IT's nopt theory but fact, easily proven by any shooter. Take your fav. handgun & load heavy bullets & light bullets at the same vel. You'll find that most of the time, most of the guns, the heavier bullet shoots higher. It's not bbl time, the vel is the same, it's bullet mass, recoil. If you were somehow to lock the gun in a non recoiling fixture, then obviously recoil palys no part in the equation & POI are likely to be the same.

[mpmarty]

IT's nopt theory but fact, easily proven by any shooter. Take your fav. handgun & load heavy bullets & light bullets at the same vel. You'll find that most of the time, most of the guns, the heavier bullet shoots higher. It's not bbl time, the vel is the same, it's bullet mass, recoil. If you were somehow to lock the gun in a non recoiling fixture, then obviously recoil palys no part in the equation & POI are likely to be the same.

I believe we have a winner here folks.
Interestingly I have a 7mm Rem Mag w/28" bbl that shoots 110 and 160 gr Jwords into the same elevation and pretty much the same hole w/max loads of 870 in the heavy and 4064 in the light loads. This rifle is a safe queen as I have no real use for it any longer. I built it some twenty years ago on a Howa action (think Weatherby Vanguard).