Thank you sir! I was just asking! I don't need to see proof.
Bullet Construction vs Lethality
- Thread starter nralifer
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nralifer
Well-Known Member
Should work as well.
I don't recall that video. I would be interested in seeing it.
Was it just one shot each? What are all the missing details? All I know is it was the 199gr Hammer (assuming Hunter) and that it was 200fps faster than the Berger (assuming that's the 215gr bullet being referred to).
For discussion sake, I would like to know if they were fired from the same rifle, or were there twin rifles and were they fired at the exact same time side by side at the same target and point of aim? What was the actual MV for each bullet? Was the velocity of each recorded as they were shot? What is the muzzle velocity extreme spread on the ammo loaded? I would also like to know what the exact wind conditions were. Was the wind variable? What was the distance to the target? What was the target? How was the impact recorded and how do we know that the point of aim was actually where the reticle was when the bullet exited the muzzle? How do we know the person on the trigger didn't negatively influence the rifle and this point of impact? The list goes on and on. Surely the point is made, but these are valid and important pieces to the equation.
It should be obvious by all those questions that there are so many variables affecting the results in a "backyard test". Wind is not constant. Shooter input is not perfect. To get reliable test results, we need to reduce as many variables and negative influencers as possible. We need as much accurate data input as possible too. Garbage in, garbage out, right?
Math and physics do not lie. Just because you see a different result out in the field, it does not mean the math and physics are wrong. It does not mean BC isn't able to calculate hold for wind drift. It means wind isn't constant and your input, and thus output, for hold is only accurate for that particular value of wind. If that value changes, the result will change.
Gravity is constant. Calculating drop is way more accurate as a result. Shooter error and errors to inputs can still mess with that result too though.
Hammer at 3100fps, 10mph full value wind.Berger at 2900fps, 10mph full value wind.As you can see, there's barely a difference to 300 yards in the calculated wind drift. And at 500 yards it's a 1.2" difference between the two. That can easily be swayed, and drastically, just by shooter error, or a change in wind, etc.
It's a 6.9" difference between the two at 1000 yards. If your extreme spread on your ammo is 30fps, that equates to a 1" difference alone in drift at 1000 yards. When you factor in other negative influences, it can compound into a huge difference, even at closer range.
So are we really going to say BC is the problem? Are we really to believe BC just doesn't account for drift? I don't buy it. There are simply too many other highly plausible explanations for the unexpected point of impact.
If you ran that test multiple times, under the same conditions, I'd bet you get many different results. Statistically, it only makes sense. Increase your sample size and let's see what happens. I'll bet there are times you see what is expected based on your ballistic calculator, other times you'd see more drift than calculated, and still other times you'd see less drift than calculated- and by either bullet.
This is not me just trying to argue. This is me disagreeing and offering my explanation as to why I disagree. It also makes no difference who said it. I'm referring only to what was said.
I welcome further debate on this subject because I find it pretty fascinating. I'm willing to be wrong and learn something new. I'm just not convinced yet. Chapter 5 of "Applied Ballistics for Long-Range Shooting" made a lot of sense to me
.
Wd= 17.6 * Ws * Tlag
Where:
Wd = wind deflection (inches)
Ws = crosswind speed (mph)
Tlag = Lag time (seconds)
This is the formula that ballistic calculators use to calculate drift and the corresponding correction. They also calculate lag time (based on time of flight) and use that for the equation.
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Hand Skills
Well-Known Member
If I am reading this right;
ToF (time of flight) for the 199gr Hammer is 1.313sec to 1000yd in the above table
ToF on the 215gr bullet is 1.340sec to 1000yd
That is .027 sec, or 27 milliseconds 'difference'.
If ToF was the driving factor in the wind drift formula, these two bullets would have near identical drift in the same conditions. If anything, the 199gr bullet would drift slightly less than the 215ge bullet because it gets to the target faster.
...yet the calculator predicts 5.8 moa for the 199gr bullet and 5.1 for the 215.
Can anyone explain how Tlag or 'lag time' is defined?
ToF (time of flight) for the 199gr Hammer is 1.313sec to 1000yd in the above table
ToF on the 215gr bullet is 1.340sec to 1000yd
That is .027 sec, or 27 milliseconds 'difference'.
If ToF was the driving factor in the wind drift formula, these two bullets would have near identical drift in the same conditions. If anything, the 199gr bullet would drift slightly less than the 215ge bullet because it gets to the target faster.
...yet the calculator predicts 5.8 moa for the 199gr bullet and 5.1 for the 215.
Can anyone explain how Tlag or 'lag time' is defined?
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Yes
Sorry. It was late last night and I didn't include more that would answer that for you. So here that is:
So first of all, Lag time (Tlag) is defined as the difference between actual ToF and the ToF in a vacuum.
So Tlag in the formula posted earlier is not simply ToF. To get Tlag, the equation is:
Tlag = ToF - ToFvac
To calculate ToFvac, divide the distance, in feet, by the MV of the bullet.
•For the Hammer:
ToFvac = 3000/3100 = 0.9677 (rounded)
Tlag = 1.313 - 0.9677 = 0.3453
So now to get the wind deflection:
Wd = 17.6 * 10 * 0.3453 = 60.77"
•For the Berger:
ToFvac = 3000/2900 = 1.0355 (rounded)
Tlag = 1.340 - 1.0355 = 0.3045
Wind deflection:
17.6 * 10 * .3045 = 53.59"
So, due to things like the higher BC of the Berger, the lag time is ultimately lower, and thus the amount of calculated drift is lower. As stated in my earlier post, there are many other factors and variables that affect actual POI, however.
sodakota
Well-Known Member
Most of the bullets for long range are really poor for closer range shooting.
nralifer
Well-Known Member
Calculating wind drift in any ballistic app is only a theoretical number. The calculation assumes the wind is uniform in speed and direction from the shooter to the target. Since all wind follows the contour of the land, the only time when wind is uniform in direction is when the land contour is flat with no trees. I have seen wind, in undulating terrain, travel in opposite directions in between the shooter and target. Best observed in ELR matches with high quality spotting scopes. 1000 yard shots are best reserved for calm conditions. Things like mirage, long tall grass and tree branches can all give one the direction of the wind at the target but only if you have optics that can clearly image those objects. Uneven hilly terrain can cause vortices in wind direction which leads to varying direction of wind flow between target and shooter. Hunting is a skill that demands not only accuracy at distance, but the ability to get close enough to your target to have a reasonable probability to place the first cold bore shot accurately. On a windy day in the mountains or hills that means stalking your target stealthily enough to get in range such that the wind is as minimal a factor in influencing the accuracy of the shot. A hunter's skill at closing the distance between him and the target on a gusty windy day does much more for accurate bullet placement than any ballistic app. I can back up this statement with a real life hunting experience of my own while hunting Pronghorn Antelopes.I don't recall that video. I would be interested in seeing it.
Was it just one shot each? What are all the missing details? All I know is it was the 199gr Hammer (assuming Hunter) and that it was 200fps faster than the Berger (assuming that's the 215gr bullet being referred to).
For discussion sake, I would like to know if they were fired from the same rifle, or were there twin rifles and were they fired at the exact same time side by side at the same target and point of aim? What was the actual MV for each bullet? Was the velocity of each recorded as they were shot? What is the muzzle velocity extreme spread on the ammo loaded? I would also like to know what the exact wind conditions were. Was the wind variable? What was the distance to the target? What was the target? How was the impact recorded and how do we know that the point of aim was actually where the reticle was when the bullet exited the muzzle? How do we know the person on the trigger didn't negatively influence the rifle and this point of impact? The list goes on and on. Surely the point is made, but these are valid and important pieces to the equation.
It should be obvious by all those questions that there are so many variables affecting the results in a "backyard test". Wind is not constant. Shooter input is not perfect. To get reliable test results, we need to reduce as many variables and negative influencers as possible. We need as much accurate data input as possible too. Garbage in, garbage out, right?
Math and physics do not lie. Just because you see a different result out in the field, it does not mean the math and physics are wrong. It does not mean BC isn't able to calculate hold for wind drift. It means wind isn't constant and your input, and thus output, for hold is only accurate for that particular value of wind. If that value changes, the result will change.
Gravity is constant. Calculating drop is way more accurate as a result. Shooter error and errors to inputs can still mess with that result too though.
View attachment 492128
View attachment 492130
As you can see, there's barely a difference to 300 yards in the calculated wind drift. And at 500 yards it's a 1.2" difference between the two. That can easily be swayed, and drastically, just by shooter error, or a change in wind, etc.
It's a 6.9" difference between the two at 1000 yards. If your extreme spread on your ammo is 30fps, that equates to a 1" difference alone in drift at 1000 yards. When you factor in other negative influences, it can compound into a huge difference, even at closer range.
So are we really going to say BC is the problem? Are we really to believe BC just doesn't account for drift? I don't buy it. There are simply too many other highly plausible explanations for the unexpected point of impact.
If you ran that test multiple times, under the same conditions, I'd bet you get many different results. Statistically, it only makes sense. Increase your sample size and let's see what happens. I'll bet there are times you see what is expected based on your ballistic calculator, other times you'd see more drift than calculated, and still other times you'd see less drift than calculated- and by either bullet.
This is not me just trying to argue. This is me disagreeing and offering my explanation as to why I disagree. It also makes no difference who said it. I'm referring only to what was said.
I welcome further debate on this subject because I find it pretty fascinating. I'm willing to be wrong and learn something new. I'm just not convinced yet. Chapter 5 of "Applied Ballistics for Long-Range Shooting" made a lot of sense to me
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nralifer
Well-Known Member
Would have been instructive if you stated at least the BC differences between ghe two bullets.
nralifer
Well-Known Member
Most, but not all. There is a significant difference in the behavior after impact between lead core and all copper, and even between lead core bullets and the way in which they are constructed. Same thing with all copper. High BC in lead core bullets coupled with high MV is detrimental to the short range performance after impact for lead core bullets whereas at longer ranges say 500 yds and beyond, the high BC becomes an asset for lead cores because they slow down to the point that the soft lead does not behave like a paste, but will have less drop and wind drift. A properly constructed hollow point and tip that gives very reliable expansion both at close range, say within 400 yds, and long range, say beyond 500-600 yds up to 1000 yds, in an all copper bullet will give that bullet a much wider performance envelope and better penetration than a lead core.
nralifer
Well-Known Member
Explain the "17.6". Looks like it is a dimensionless constant. Nice post, by the way.
nralifer
Well-Known Member
The difference in wind defection between the two bullets at 1000 yds seems significant (7.18") given that the size if the vitals area in large game is usually 10" wide. Am I interpreting things correctly?
It's a conversion factor to get the solution to be in inches.
