Bullet weights?

pblanc · Dec 18, 2019

Very well. Change bore axis to "axis of the bore". What I was saying is that if the bore of two different barrels were not absolutely concentric, it could be a possible mechanism for the slower projectile hitting higher.

You keep focusing on the sight heights on the different barrels and what I keep trying to get across is that the particular sights do not enter into the issue I am discussing. Forget about the fact that I have two different slides with different sights, because I can shoot 40 S&W and 357 SIG from both. I am not talking about a change in POI resulting from a change in sights.

The point is that in the P229 and P226 the exact same pistol (except for barrel) with the exact same sights will shoot the slower 40 S&W cartridge to a higher POI than the faster 357 SIG cartridge when using the same sight picture and shooting at the same intermediate range. Choose whatever sights you wish because they are the same for the two cartridges after just swapping the barrel. This has been observed by umpteen owners of these pistols who have changed from one cartridge to the other with only a barrel swap. I provided a few links to threads that discuss this. I could provide many more if I wanted to waste my time. I don't know how else to say this.

If as you say there is no change in barrel orientation during the internal ballistic phase, by what mechanism do you suggest that the same pistol with the same barrel orientation at ignition will shoot a slower projectile to a higher POI than a faster one?

Walt Sherrill · Dec 18, 2019

pblanc said:
The point is that in the P229 and P226 the exact same pistol (except for barrel) with the exact same sights will shoot the slower 40 S&W cartridge to a higher POI than the faster 357 SIG cartridge when using the same sight picture and shooting at the same intermediate range. Choose whatever sights you wish because they are the same for the two cartridges after just swapping the barrel. This has been observed by umpteen owners of these pistols who have changed from one cartridge to the other with only a barrel swap. I provided a few links to threads that discuss this. I could provide many more if I wanted to waste my time. I don't know how else to say this.

Bore axis and axis of the bore are the same thing. You seem to think the differences in point of impact are due to one of the barrels being improperly made.

At 25 yards SIG's sights are set so that point of aim and point of impact are the same. Most ammo makers use that same point of coincidence. Some ammo makers, like PMC, 50 yards. Depending on the ammo used and the sight system the rounds of the two calibers should hit the same point of impact at the same place, using the proper sights for the barrel used.

When using either barrel in the .40 S&W slide, or the .357Sig slide, the differences between the two groups of rounds shot should be the same for either slide and sight set at any given distance, regardless of the slide used, but the points of impact will be higher or lower than the prior group' of shots done with a different sight set.

Why does a heavier/slower round hit higher than a faster light and the bullet trajectories. The rounds used send the bullets out of the gun on different trajectories, and the different sights raise or lower the points of impact for either type of round.

But the differences between the two rounds vary -- as you get farther and farther away from the muzzle. This can be seen in the PMC chart shown here, which uses 50 yards as the zero point. (I used this chart to make the arc of the bullet bath easier to see -- starting out HIGHER than the point of AIM but eventually getting lower and lower. You'd probably need adjustable sights to actually verify the PMC ballstic chart yourself.

Here's how things differ, but you can see this for yourself looking at the chart. The point of aim in this example is the 25 yard point.

At 25 yards:

The fastest and lightest PMC .357Sig round (124 gr @ 1040 fps) hits the lowest round hits 0.45" above the point of aim.
The fastest and lightest 40 S&W round (155 gr. @ 1160 fps) hits the target 0.65" above the point of aim
The heaviest and slowest 40 S&W self defense round (180 gr. @ 985 fps) hits the target at 0.94" above the point of aim.

At 50 yards:

All three rounds hit the point of aim -- or 0.0".

At 75 yards:

The fastest and lightest .357Sig round has dropped to 2.07" below the point of aim.
The fastest and lightest 40 S&W round has dropped to 3.44" below the point of aim.
The heaviest and slowest self defense 40 S&W round hits 3.45" below the point of aim

At 100 yards:

The fastest and lightest .357Sig round has dropped to 5.95" below the point of aim.
The fastest and lightest 40 S&W round has dropped to 7.47" below the point of aim.
The heaviest and slowest self defense 40 S&W has dropped to 9.58" below the point of aim

The .357 SIG slide has a taller front sight (#6) than the .40 slide (#8). Either round fired from that slide should hit about 1" lower at 25 yards. than if the same barrel and rounds are fired from the .40 slide, which has a lower front sight.

The relationship (groupings) of the .357 SIG rounds to the .40 round shot from that slide should be the same, but the group from that slide should hit about an inch lower at 25 yards (SIG and the SIG Forum and other web sites will tell you that with SIGs, a front sight number that is lower is taller than one with a number one # up; that lowers POI about 1 inch per number down at 25 yards.

pblanc said:
If as you say there is no change in barrel orientation during the internal ballistic phase, by what mechanism do you suggest that the same pistol with the same barrel orientation at ignition will shoot a slower projectile to a higher POI than a faster one?

That is caused by the normal mechanism that always affects the bullet path: velocity, bullet weight, gravity, and how the sights change the point of aim.

The point you continue to overlook is that the bullet paths (trajectories) vary with the round used. The bullet weight, it's velocity changes the trajectory.

The .357SIG round takes a lower trajectory, and the arc of the bullet's travel (It's path, similar to an arc) drop is less pronounced than the .40 round. The sights on the .40 slide lower the front sight so that the barrel starts at a slightly higher angle than does the .357 slide, which has a higher front sight. The different sights change where the shots start, but not the path they follow!

If you graph the trajectories of the PMC rounds, you'll see that both rounds were above the 50 yard point of aim at 25 yards, but both have dropped to hit the point of aim at 50 yards. Then they continue their downward path, but at different rates.

Now, you can tell us why bore axis should have any effect on the point of impact, since recoil has only an almost trivial effect on the barrel's position until after the bullet is gone when the gun uses a Browning Short Recoil Locked Breech mechanism. Recoil is delayed, allowing the bullet to leave the gun with only a small amount of recoil force transferred to the frame.

35 Whelen · Dec 18, 2019

The subject of bullet impact where handguns are concerned is sort of like that of bullet energy; math, charts and physics have little to do with real world results.

I shoot identically configured SA revolvers, that is both with 5 1/2" barrels, one in 32-20 and one in 45 Colt, same sight height, and there are different POI's between the two, but not in a way that math and physics would indicate. The 32-20 loads, whose bullets are typically running a couple hundred fps faster than those of the 45 Colt, strike lower. There are a couple of reasons for this.

First the smaller caliber revolver is heavier because there's more metal present in the cylinder and barrel due to the smaller chambers and smaller hole in the barrel, which adds weight, which in turn reduces recoil and muzzle rise, in addition to the fact that the lighter bullet recoils less. On the other hand, the revolver chambered in 45 Colt is lighter because of less metal due to the larger holes in the chambers and barrel, which of course increases recoil. Second, the larger caliber revolver recoils more because of the heavier projectiles in addition to the lighter weight of the revolver. So, the slower heavier bullet impacts higher than the light fast one, converse to what charts would indicate.

Mathematically, at typical handgun ranges, there's little difference in POI's of most handguns, but in the real world math is just math.

The point of all this is, go out and shoot and see the difference.

35W

Walt Sherrill · Dec 18, 2019

35 Whelen said:
I shoot identically configured SA revolvers, that is both with 5 1/2" barrels, one in 32-20 and one in 45 Colt, same sight height, and there are different POI's between the two, but not in a way that math and physics would indicate. The 32-20 loads, whose bullets are typically running a couple hundred fps faster than those of the 45 Colt, strike lower. There are a couple of reasons for this

First the smaller caliber revolver is heavier because there's more metal present in the cylinder and barrel due to the smaller chambers and smaller hole in the barrel, which adds weight, which in turn reduces recoil and muzzle rise, in addition to the fact that the lighter bullet recoils less. On the other hand, the revolver chambered in 45 Colt is lighter because of less metal due to the larger holes in the chambers and barrel, which of course increases recoil. Second, the larger caliber revolver recoils more because of the heavier projectiles in addition to the lighter weight of the revolver. So, the slower heavier bullet impacts higher than the light fast one, converse to what charts would indicate..

If, by handgun ranges, you mean less than 20-25 yards, I agree. It probably also depends on which charts you're using, and the distances at which your doing your comparisons. I don't know (have never really examined) the role a revolvers's barrel/frame weight plays in barrel rise, but it certainly has to play SOME role.

Most ballistic charts don't really address bullet paths at distances less than 25 yards. I used the PMC chart in my replies above because that CHART did show points of impact before the bullet reached the desired point of impact (i.e., 50 yards).

As noted earlier, a fixed barrel gun's recoil starts to raise the barrel as soon as the bullet starts down the barrel. Recoil force transfer to the frame start immediately and continues while the bullet moves down the barrel.

The semi-autos we're talking about don't get that big IMMEDIATE transfer of recoil force to the frame because the Browning Short Recoil Locked Breech's design delays recoil substantially until the bullet is out of the barrel. With most BSRLB guns, the bullet and slide will have moved less than 1/10th of an inch to the rear before the bullet leaves the barrel. Not much recoil force is transferred to the frame during that small amount of barrel/slide travel. The rest is transferred to the frame after the bullet is gone (and it can't have much affect on the bullet.)

But, once the fixed barrel's bullet is on it's own, the bullet trajectory of the load used (bullet weight and bullet velocity) comes into play. And like the .357Sig and .40 rounds being discussed in prior exchanges, the trajectories of the two rounds you describe are going to be quite different But it will be hard to see a difference at closer ranges, like anything under 20 or 25 yards.

pblanc · Dec 19, 2019

Walt Sherrill said:
Bore axis and axis of the bore are the same thing. You seem to think the differences in point of impact are due to one of the barrels being improperly made.

At 25 yards SIG's sights are set so that point of aim and point of impact are the same. Most ammo makers use that same point of coincidence. Some ammo makers, like PMC, 50 yards. Depending on the ammo used and the sight system the rounds of the two calibers should hit the same point of impact at the same place, using the proper sights for the barrel used.

When using either barrel in the .40 S&W slide, or the .357Sig slide, the differences between the two groups of rounds shot should be the same for either slide and sight set at any given distance, regardless of the slide used, but the points of impact will be higher or lower than the prior group' of shots done with a different sight set.

pblanc · Dec 19, 2019

No, I do not think that the difference in point of impact is a result of barrels with non-concentric bores.

The vertical difference in the point of impact of 357 SIG and 40 S&W is not explained by how the pistol is sighted or the particular sights on the slide. Of course, the point of impact relative to the point of aim will depend on the height of the front and rear sights, the height of the sight axis above the bore axis, and the particular sight picture used. But in the SIG P226 and P229 the 40 caliber cartridge hits at a higher POI than the 357 SIG regardless of the particular sights when using the same slide and the same sights to shoot both cartridges.

This is not explained by ballistic drop due to gravity since the slower moving cartridge would be expected to drop more over any given distance than the faster cartridge, although at ranges of 15 yards the drop will not be very much.

If I take a P226 or a P229 pistol with any given set of sights, and shoot both 40 S&W and 357 SIG through it at 15 yards with only a barrel change using the proper sight alignment and good trigger control and the same sight picture, I think it is reasonable to assume that the orientation of the barrel at ignition will be the same. Once again, the sights are not changing between the two cartridges, nor is the range, nor is the sight picture.

You are confusing the issue by talking about how different sights are often used for the two different cartridges and how that affects the ballistic path relative to the sight line. In your ballistic table example the faster 357 SIG cartridge (which has a muzzle velocity of 1350 fps, not 1040 fps by the way) and the slower 40 S&W cartridge are being shot out of pistols with different sights. In order for both cartridges to impact at the same zero point of 50 yards, the bore axis has to be more steeply inclined relative to the sight line for the slower cartridge because of its greater drop due to gravity over that distance. So the slower cartridge's ballistic path intersects the sight axis at a shorter range and that is why its point of impact is higher at 25 yards. Both bullets are accelerated toward the center of the earth at exactly the same rate as soon as they leave the barrel so the slower 40 projectile has actually deviated further from its original flight path at 25 yards than the faster 357 SIG projectile has.

Of course, all of that is true but that is not relevant to what I am discussing here because the sights are not changing between the two cartridges. If the sights remain constant, the orientation of the barrel when the trigger is pulled remains the same for both cartridges. But the slower cartridge will impact higher at 15 yards. This has been documented by umpteen P226 and P229 owners who have swapped barrels without changing sights.

If the orientation of the barrel at ignition is identical for the two cartridges, then the only way that the slower cartridge can impact higher is if the orientation of the barrel changes before the projectile leaves the barrel. The barrel would have to be inclined at a greater angle for the slower projectile to hit higher.

QED · Dec 19, 2019

pblanc said:
Of course, all of that is true but that is not relevant to what I am discussing here because the sights are not changing between the two cartridges. If the sights remain constant, the orientation of the barrel when the trigger is pulled remains the same for both cartridges. But the slower cartridge will impact higher at 15 yards. This has been documented by umpteen P226 and P229 owners who have swapped barrels without changing sights.

If the orientation of the barrel at ignition is identical for the two cartridges, then the only way that the slower cartridge can impact higher is if the orientation of the barrel changes before the projectile leaves the barrel. The barrel would have to be inclined at a greater angle for the slower projectile to hit higher.

According to your view, if the sights are fixed, and the barrel axis is fixed, how much would the barrel have to be more torqued up during bullet travel in the barrel if you have, say, one bullet at 1000 fps mv and another at 1300 fps mv, in order to have non-trivially higher point of impact for bullet at 1000 fps mv at 15 yards?

pblanc · Dec 19, 2019

Those P22x shooters that swap barrels and observe a change in POI between .40 S&W and 357 SIG report varying differences. Obviously, it is going to depend on what ammunition they are comparing. The difference between a fairly fast 165 grain .40 and a somewhat watered down 357 SIG (as many commercial varieties of that caliber seem to be) will be less. Those who are into combat style shooting might not really notice much difference unless they start firing slow fire for groups. And those who just stick with the 357 SIG barrel without changing sights may just alter their hold a bit without really thinking much about it.

But everyone that I have heard report an observed difference find that the 357 SIG impacts lower with the same sights, and sight picture. I have heard some say that they have seen a difference of as much as 2" at around 25 yards. The difference I have observed is less, between .75 and 1 inch at around 15 yards, the 357 SIG again hitting lower. I am most often shooting Speer Lawman 125 grain 357 SIG with a claimed muzzle velocity of 1350 fps. I have shot a wide variety of .40 S&W but almost all of it has been 180 grain, usually with an advertised muzzle velocity a bit less than 1000 fps. So we are talking about a difference in muzzle velocity of around 400 fps or a bit less.

Since 15 yards is 540 inches, a one inch change in POI vertically would require an angular change in barrel orientation equivalent to the inverse tangent of 1/540 which is about one tenth of one degree. A change in POI of .75 inches would require an angular change of about .0625 degrees.

So the short answer is "not much".

QED · Dec 19, 2019

pblanc said:
Those P22x shooters that swap barrels and observe a change in POI between .40 S&W and 357 SIG report varying differences. Obviously, it is going to depend on what ammunition they are comparing. The difference between a fairly fast 165 grain .40 and a somewhat watered down 357 SIG (as many commercial varieties of that caliber seem to be) will be less. Those who are into combat style shooting might not really notice much difference unless they start firing slow fire for groups. And those who just stick with the 357 SIG barrel without changing sights may just alter their hold a bit without really thinking much about it.

But everyone that I have heard report an observed difference find that the 357 SIG impacts lower with the same sights, and sight picture. I have heard some say that they have seen a difference of as much as 2" at around 25 yards. The difference I have observed is less, between .75 and 1 inch at around 15 yards, the 357 SIG again hitting lower. I am most often shooting Speer Lawman 125 grain 357 SIG with a claimed muzzle velocity of 1350 fps. I have shot a wide variety of .40 S&W but almost all of it has been 180 grain, usually with an advertised muzzle velocity a bit less than 1000 fps. So we are talking about a difference in muzzle velocity of around 400 fps or a bit less.

Since 15 yards is 540 inches, a one inch change in POI vertically would require an angular change in barrel orientation equivalent to the inverse tangent of 1/540 which is about one tenth of one degree. A change in POI of .75 inches would require an angular change of about .0625 degrees.

So the short answer is "not much".

Not much at all would be the difference in barrel tilt if you push the slide back 0.09" vs. 0.07" -- approximately corresponding to effect on the slide for bullets with two referenced velocities before exiting the barrel. In both cases the spring is hardly compressed at all, exerting only a barely perceptible force. There is simply no accounting for forces that would be needed to cause any significant barrel up tilt to make the slower bullet impact actually higher than the faster.

pblanc · Dec 19, 2019

Well then, what is your explanation for why it happens? Because it has been reported many, many times.

It is really annoying to be repeatedly told that something which I have repeatedly observed, as have many others, Is impossible. Take a look at the links I posted. Or do your own research on this issue. Or don't and continue to believe what you "know".

I am finished with this discussion. Bye.

QED · Dec 19, 2019

pblanc said:
Well then, what is your explanation for why it happens? Because it has been reported many, many times.

It is really annoying to be repeatedly told that something which I have repeatedly observed, as have many others, Is impossible. Take a look at the links I posted. Or do your own research on this issue. Or don't and continue to believe what you "know".

I am finished with this discussion. Bye.

Hardly everyone has experienced or reported this barrel tilt up effect due to typical "longer bullet time in barrel"; if indeed it were really significant in semis (as reported by some), consider that this effect in revolvers is considerably more than an order of magnitude greater. Although this apparent effect may exist to some minor extent depending on particular pistol tolerances and particular ammunition, there is no "immediate retrograde force applied to breech block" that could cause anything close to 1" higher POI for bullet at 1000 fps vs. 1300 fps @ 25 yards (for same slide/sights and bore axis before firing). Cheers.

Walt Sherrill · Dec 19, 2019

I know you've dropped out of this discussion, but...

pblanc said:
You are confusing the issue by talking about how different sights are often used for the two different cartridges and how that affects the ballistic path relative to the sight line. In your ballistic table example the faster 357 SIG cartridge (which has a muzzle velocity of 1350 fps, not 1040 fps by the way) and the slower 40 S&W cartridge are being shot out of pistols with different sights. In order for both cartridges to impact at the same zero point of 50 yards, the bore axis has to be more steeply inclined relative to the sight line for the slower cartridge because of its greater drop due to gravity over that distance. So the slower cartridge's ballistic path intersects the sight axis at a shorter range and that is why its point of impact is higher at 25 yards. Both bullets are accelerated toward the center of the earth at exactly the same rate as soon as they leave the barrel so the slower 40 projectile has actually deviated further from its original flight path at 25 yards than the faster 357 SIG projectile has.

All that is true.

The test barrels used by PMC are elevated for the PMC ballistic chart so that the point of aim and point of impact -- for each round shown on the chart -- coincide at 50 yards. SIG did something similar with those two SIG slides -- one is set so that a "general"40 S&W round hits at 25 yards, and the other is set so that "general" .357SIG round hits at 25 yards. (I used the PMC chart because I couldn't find a ballistic chart that showed the bullet paths BEFORE the 25 yard mark.)

The bullets begin to drop as soon as they leave the barrel. In the SIG slides or in the test barrels, the barrels are tilted up a bit so the drop isn't obvious. But for the heavier/slower rounds to hit the desired point of impact, the bullet must travel using a higher arc than the faster/lighter rounds. That higher arc means the front of the heavier/slower round's barrel must be a bit higher to hit that 50 yard point of aim. And that heaver/slower bullet's higher arc will be seen BEFORE and at 25 yard mark and the two won't coincide until they both hit the 50 yard mark.

By using the same slide/sights with both barrels, and then changing to the other slide and sights doesn't change the paths the bullets travel; their respective arcs are dictated by physics and the chemistry of the powders used -- but the slide with the lowest front sight will make the bullets from that slide hit higher.than the bullets fired from the other slide. And depending on where the target is positioned, the heavier/slower round will hit higher or lower than the lighter/faster round. At closer distances, the heavier/slower bullet might obviously hit higher than the faster/slower round -- but only because the target is close, and the sights have raised the front of the bullet a bit more.

IF both guns were shot with their barrels absolutely level (with no barrel tilt due to the sights) the heavier/slower bullet would perform exactly as you expect -- dropping more quickly than the faster, lighter round.

But those SIG slide don't make the barrels level. No gun sights do. (The #8/#8 sights on the .40 slide don't make the barrel level because the #8 (.40) front sight is lower than the #6 (.357 SIG) front sight, and the .40 barrel in that slide is elevated a bit higher than the sights on the SIG slide when aiming at the same target. When you fire the .357 SIG round through the.40 barrel/slide combo, it's also higher than when fired through the .357SIG slide/barrel, but the difference between the .40 and .357 points of impact should be the same. should be the same with either slide.

Nobody is saying you didn't see what you saw, or that others don't see it, too. We're just saying that you're misinterpreting what you see, by 1) focusing on differences in points of impact that are tied to the sights being used, and 2) ignoring how those differences change as the target is moved out. The path a .40 round follows to hit a 25 yard target is a higher arc than the path a .357SIG round follows to hit the same target. You've focused on the front end of those paths, and not the entire path.

pblanc · Dec 20, 2019

No Walt, that does not wash.

Yes SIG tends to sight their pistols in at 25 yards and in general a change of one sight number on the front sight roughly changes point of aim by 1"at that range, per SIG. So changing the front sight from a #6 to a #8 should in theory raise the POI by 2", the #8 sight being shorter. But since I have five SIG pistols and have changed sights on several of them, I know that that is not entirely true. For one thing, it depends on the sight radius. The effect of that sight change on the P226 with a longer sight radius will be less than on a P229, which will be less than on a P320 or P250 subcompact which will be less than on a P365. And what I have observed is that going from a #6 to a #8 sight on the P229 will shift POI by somewhat less than 2" at 25 yards. But that is beside the point.

I understand the point you are trying to make. But it does not apply for pistols sighted in at 25 yards. Go the the Federal Ballistic Calculator here:

https://www.federalpremium.com/ballistics-calculator

Select "factory loads" under load type, then select either 40 S&W or 357 SIG under "caliber" and "FMJ" for bullet type. For 40 S&W pick "180 grain" for bullet weight. 357 SIG will default to a bullet weight of 125 grains. The default muzzle velocity for 40 S&W will be 1000 fps for the 180 grain with a G1 BC of .170. For 125 grain, the default muzzle velocity will be 1350 fps with a G1 ballistic coefficient of .150.

For either cartridge, choose 25 yards as the zero range. Change the sight height from 0.9" to 0.6" which is much closer to what the sight axis offset from bore is for the P229 pistol. Reduce the range interval to 5 yards and leave all the other values at the default settings. Run the calculations for both cartridges.

If you do that, here is what you will get. The drop at each range is in inches above or below the sight axis, the range values are in yards:

For 180 grain, 40 S&W FMJ: range/ drop
5 -0.6
10 -0.3
15 -0.1
20 +0.1
25 0.0
30 -0.2
50 -1.7
100 -12.5

For the 125 grain, 357 SIG FMJ: range/ drop
5 -0.4
10 -0.2
15 -0.1
20 0.0
25 0.0
30 0.0
50 -0.8
100 -7.0

If you don't believe those numbers, run them yourself. Or use a different ballistic calculator if you wish, although I have found Federal's to be one of the best, and I have used quite a few of them.

So you see from those numbers that for pistols sighted in for a 25 yard zero, there is absolutely no difference in POI at 15 yards. The difference in POI at 10 and 20 yards is very small, only .1" and barely a quarter of the width of a bullet hole. Certainly nothing that anybody other than a precision shooter would ever be able to notice. The maximum ordinate for the 40 S&W cartridge is at 20 yards and max Y for the 357 SIG is right at the zero point of 25 yards. Also notice that at longer ranges, the lesser drop of the faster cartridge starts narrowing the difference in POI so that by 50 yards a .9" difference in POI, which is about what I have observed with the SIG P229 at 15 yards, is completely canceled out by the greater drop of the 40 S&W cartridge (1.7-0.8=0.9). This too is consistent with what I have observed.

So at ranges of 10-25 yards there is no, or a negligible difference in ballistic path for these two cartridges for pistols zeroed at 25 yards for all ranges from near point blank to the zero range. Yet to achieve that 25 yard zero SIG Sauer puts a shorter front sight on the P229 chambered in 357 SIG than they do for the same pistol chambered in 40 S&W. They do this to elevate the POI for the 357 SIG cartridge because they know that it will impact lower than .40 S&W at the ranges most people are shooting at, 25 yards or less. At ranges much beyond the 25 yard zero, the ballistic path of the two cartridges diverges significantly due to the effect of gravity.

Walt Sherrill · Dec 20, 2019

pblanc said:
Select "factory loads" under load type, then select either 40 S&W or 357 SIG under "caliber" and "FMJ" for bullet type. For 40 S&W pick "180 grain" for bullet weight. 357 SIG will default to a bullet weight of 125 grains. The default muzzle velocity for 40 S&W will be 1000 fps for the 180 grain with a G1 BC of .170. For 125 grain, the default muzzle velocity will be 1350 fps with a G1 ballistic coefficient of .150.

All of the loads listed on the PMC chart are FACTORY LOADS, but for a given caliber there are significant differences in the bullet paths described. That's why I said SIG uses a "generalized" .40 round for their sights. No one sight set will be correct for the many different factory loads available in a given caliber.

And it seems you're focused on 25 yards only. Some bullets (depending on their sights) may still be climbing at that distance, and others will be starting down before they get that far. That's why the right sights are critical. In your .40 chart above, the .40 round had already started DOWN before it hit the 25 yard mark (given that it was .01" high at 20 yards and on target as the 25 yard mark... A different sight set might move the point of impact from 25 yards to 20 yards if the target is set at 20 yards.

With the PMC chart you can see that the differences between the different bullet paths for various loads at 25 yards (when the round are supposed to have POA/POI the same at 50 yards are quite significant (and far more than 1/10th of an inch.

In your analysis of your results you cherry pick the similarities while ignoring the differences. You seem to ignore the fact that the 40 round has a sharper arc than the .357Sig round.

For 180 grain, 40 S&W FMJ: range/ drop

5 -0.6
10 -0.3
15 -0.1
20 +0.1
25 0.0
30 -0.2
50 -1.7
100 -12.5

The .40 figures seem reasonable for a round that is designed to have the point of aim and point of impact coincide at 20 yards, not 25. The .40 round peaked at or near 20 yards. Different sights or a slightly different load (heavier bullet or lower velocity) might have given you 0.0" at 20 yards.

For the 125 grain, 357 SIG FMJ: range/ drop:

5 -0.4
10 -0.2
15 -0.1
20 0.0
25 0.0
30 0.0
50 -0.8
100 -7.0

I suspect there's something wrong with your .357SIG results. That chart describes an arc/bullet path that is slowly rising until it hits 20 yards -- and then stays level from 20 to 25 to 30 yards (another 30 feet before dropping again.

That can't happen, as there's no way the .357SIG (or any) round will go 10 yards without rising or falling. Unless you've found a way to overcome the laws of physics, something is wrong with your measurements shown on that chart.

pblanc said:
So at ranges of 10-25 yards there is no, or a negligible difference in ballistic path for these two cartridges for pistols zeroed at 25 yards for all ranges from near point blank to the zero range. Yet to achieve that 25 yard zero SIG Sauer puts a shorter front sight on the P229 chambered in 357 SIG than they do for the same pistol chambered in 40 S&W. They do this to elevate the POI for the 357 SIG cartridge because they know that it will impact lower than .40 S&W at the ranges most people are shooting at, 25 yards or less. At ranges much beyond the 25 yard zero, the ballistic path of the two cartridges diverges significantly due to the effect of gravity.

Any comparison of points of impact (or bullet paths) close to the muzzle are going to be similar. The differences caused by different weights and velocities (and different sights) haven't had the time or space to develop! Then, too, the guns barrels are going to be starting at different angles when the bullets are heavier or lighter.

I've done a number of tests of different bullets and loads at 20 and 30 feet, and it's hard to tell a difference at that distance regardless of caliber, bullet weight, or velocity without a Ransom Rest -- and even then any differences might be attributable to round production variances than anything else. A lot of the less expensive factory loads are really NOT target loads.

As I said before, where a bullet hits on a target is a function of the loads used, the sights used, and the distance to the target. And if the shooter isn't using a Ransom Rest, the point of impact will likely be affected by the shooter's ability to hold the sights on target through the trigger pull.

Using the same sights with two different slide/barrel sets (one with a set of .40 sights and one with a set of .357Sig sights) should show no differences in the relationship between where the 357 SIG bullet hits vs. a .40 bullet on either target -- the amount of distance between the two calibers on a given target should vary mostly with distance), but be the same on either target -- but the rounds fired from the .357 SIG slide should hit lower than the rounds fired from the .40 slide.

Garandimal · Dec 21, 2019

Like heavy for caliber bullets for three reasons.

1. Higher sectional density generally translates into better penetration.
2. Heavier bullets are generally designed to expand more, due to more bullet to work with.
3. Heavier bullets generally are less snappy to shoot, and as my 9mm Para is a micro (P938), and my .40's are compact polymer framed (G23.4's), that makes a difference in both follow-up shot time and accuracy.

GR

QED · Dec 21, 2019

Garandimal said:
Like heavy for caliber bullets for three reasons.

1. Higher sectional density generally translates into better penetration.
2. Heavier bullets are generally designed to expand more, due to more bullet to work with.

GR

But since heavier JHPs are designed to expand more, that translates into not much, if any, greater sectional density, or more penetration than somewhat lighter JHPs that expand less.

Garandimal · Dec 21, 2019

QED said:
But since heavier JHPs are designed to expand more, that translates into not much, if any, greater sectional density, or more penetration than somewhat lighter JHPs that expand less.

If you compare, say... the Std. pressure 9mm Para 124 gr. and 147 gr. HST?

You will find that there is a reasonable difference, including shootability.

GR

QED · Dec 21, 2019

Garandimal said:
If you compare, say... the Std. pressure 9mm Para 124 gr. and 147 gr. HST?

You will find that there is a reasonable difference, including shootability.

GR

147 grain HST, as you correctly state, is designed to expand more than a 124 grain HST (standard or +p); however, in doing so 147 grain HST loses greater initial sectional density and thus 124 grain HST generally penetrates more. In fact, in bare standard 10% ordnance gel 147 grain HST barely penetrates 12" as it over expands. 12" penetration -- even in standard 10% ordnance gel, no thanks. I'll take less expansion and significantly more penetration.

Garandimal · Dec 26, 2019

QED said:
147 grain HST, as you correctly state, is designed to expand more than a 124 grain HST (standard or +p); however, in doing so 147 grain HST loses greater initial sectional density and thus 124 grain HST generally penetrates more. In fact, in bare standard 10% ordnance gel 147 grain HST barely penetrates 12" as it over expands. 12" penetration -- even in standard 10% ordnance gel, no thanks. I'll take less expansion and significantly more penetration.

According to several tests, including Lucky Gunner, the 147 gr. HST performed well w/in spec. (12"-18")

It is also subsonic and noticeably easier to shoot out of a micro pistol, and the 124 gr. and 147 gr. are similar in that platform.

GR

Jonesy814 · Dec 26, 2019

Have had my 9mm Shield for 7 years. It took me a while to be able to shoot it well. Part of that was due to that 115gr ammo definitely impacts below my point of aim by about 1.5 inches at 50 feet. It is even more noticeable with a 38 revolver going from 125 to158 grain ammo. I have managed to find a midrange 130 grain load for 357 that hits pretty close to the same point as my 158 grain, near full power load

QED · Dec 27, 2019

Garandimal said:
According to several tests, including Lucky Gunner, the 147 gr. HST performed well w/in spec. (12"-18")

It is also subsonic and noticeably easier to shoot out of a micro pistol, and the 124 gr. and 147 gr. are similar in that platform.

GR

I know. But, a combination of Clear Ballistics "gel" density which is some 20% less than Fackler's gel (adopted, of course, by FBI for testing purposes with specific gravity~1.03) and with FBI's "heavy clothing" barrier results in unrealistic expansion and penetration with regard to what would happen in soft-tissue (which, of course, is where adequate penetration, minimum 12", really matters in self-defense). In any case, neither gel is an accurate tissue simulant for muscle, kidney, liver, fat,spleen, skin, tendons, ligaments, etc. etc. among just soft-tissues. A penetrating bullet, would, of course, encounter substantially greater energy loss per distance penetrated in those soft-tissues than in Clear Ballistics or Fackler's (FBI adopted) 10% ordnance gel -- and thus penetrate significantly less in tissue.

Kleanbore · Dec 27, 2019

QED said:
n any case, neither gel is an accurate tissue simulant for muscle, kidney, liver, fat,spleen, skin, tendons, ligaments, etc. etc. among just soft-tissues.

Ya think so?

So what?

QED said:
A penetrating bullet, would, of course, encounter substantially greater energy loss per distance penetrated in those soft-tissues than in Clear Ballistics or Fackler's (FBI adopted) 10% ordnance gel -- and thus penetrate significantly less in tissue.

Really?

How about glass, metal, wall-board, heavy clothing...?

QED · Dec 28, 2019

Kleanbore said:
Ya think so?

Yes, Fackler's 10% ordnance gel, ~1.03 specific gravity (4C-590 fps, 8.5cm BB pen.) used by the FBI is not an accurate soft-tissue simulant because it doesn't accurately simulate various tissues. For instance (from Maiden Ph.D.,University of Adelaide, School of Medical Sciences, 2014)
Fackler's gel (used by FBI) Fat Liver Kidney Muscle Spleen ....
Energy Loss (J/M) 90 184 115 127 121 141

So what?]

So, from basic physics, since energy loss is significantly greater in various tissues than in Fackler's gel, same projectiles would penetrate significantly less in such tissues than in Fackler's gel. And so, if 12" of soft tissue penetration is required to reach and disrupt a vital organ (through an arm perhaps) in some not-particularly-small adversary -- anything close to 12" bullet penetration capability in Fackler's gel will not do.

Really?[

Absolutely, unless Newton has been wrong all along (about simple non-relativistic mechanics that's involved here) and no one has caught on to it yet.

How about glass, metal, wall-board, heavy clothing...?

Actually, JHPs penetrating various FBI protocols barriers often penetrate more than they penetrate in bare gel -- because they expand significantly less ( or none at all) after penetrating such barriers than they expand in bare gel. And beside, sometimes the weather is not particularly cold and attackers don't wear FBI's "heavy clothing" (or conveniently have other barriers in front of them).

Kleanbore · Dec 28, 2019

QED said:
So, from basic physics, since energy loss is significantly greater in various tissues than in Fackler's gel, same projectiles would penetrate significantly less in such tissues than in Fackler's gel. And so, if 12" of soft tissue penetration is required to reach and disrupt a vital organ (through an arm perhaps) in some not-particularly-small adversary -- anything close to 12" bullet penetration capability in Fackler's gel will not do.

Significantly? I am not convinced.

And if so, why are the FBI requirements what they are? They accept 12 inches, but they prefer more.

QED said:
Actually, JHPs penetrating various FBI protocols barriers often penetrate more than they penetrate in bare gel

Of Course!

QED said:
,,,because they expand significantly less ( or none at all) after penetrating such barriers than they expand in bare gel.

No. It is because of the velocity lost in the barriers.

And if they expand "none at all", they fail the tests.

QED said:
And beside, sometimes the weather is not particularly cold and attackers don't wear FBI's "heavy clothing"

Okay.

QED · Dec 28, 2019

Kleanbore said:
Significantly? I am not convinced.

Yes, significantly -- meaning ~ 25% or greater (some tissues 100% or more) retarding force (look at the numbers I posted).

And if so, why are the FBI requirements what they are? They accept 12 inches, but they prefer more.

Habit, convenience, difference between necessary and necessary-and-sufficient, weighing factors to take into account that gel is not tissue (mechanically speaking).

Of Course!

]No. It is because of the velocity lost in the barriers.

The velocity or energy lost in protocols barriers is generally less than energy lost due to greater effective diameter of the bullet penetrating bare gel -- that's why penetration is generally less in bare gel (unless the bullet significantly fragments by some barrier, of course).

[/And if they expand "none at all", they fail the tests.

No. There is no specific requirement for expansion, only penetration (hence 9mm is acceptable.)

Okay.

The silvertip in "Miami" went into tissue with no clothing barrier; beside, nowadays JHPs are more robustly expanding so a layer or two of clothing is mostly irrelevant.

Bullet weights?

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