How many people look at BCs only. Do you try to cheat by going a lower BC with more velocity to cut down in time of flight. Does this not do the same thing as a higher BC?
Inputs on this thought.
Inputs on this thought.
BCs and time of flight
- Thread starter dar1246
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Re: BCs and time of flight
You'll have to run the numbers in JBM or another program on a case by case basis. And then you'll have to verify your testing in the field to be certain, but there probably are cases where a lower BC bullet pushed to a higher speed would outperform a higher BC bullet. But only for a time. If you shoot far enough the high BC bullet will catch and pass the lower.
Another factor is wind. I shoot 208 Amax's (.648 G1) at 2870. My shooting partner 200 SMK's (.565 BC) at over 3000 fps. My wind hold at 1500 yards is nearly half of his.
John
You'll have to run the numbers in JBM or another program on a case by case basis. And then you'll have to verify your testing in the field to be certain, but there probably are cases where a lower BC bullet pushed to a higher speed would outperform a higher BC bullet. But only for a time. If you shoot far enough the high BC bullet will catch and pass the lower.
Another factor is wind. I shoot 208 Amax's (.648 G1) at 2870. My shooting partner 200 SMK's (.565 BC) at over 3000 fps. My wind hold at 1500 yards is nearly half of his.
John
Re: BCs and time of flight
Here's my approach.
I trust BC's to within a percent or two. By that I mean the first digit is solid, the second is close to within +/-1 or 2, and the third digit is fantasy.
This is to say that assuming the published number is not poppycock, production variations should match it to within 1% or 2%.
Understand also that BC is not a fixed value, but varies within a range as a product of changing velocity.
Like chrono numbers, BCs are reliable as a comparison; but as an absolute value, not so much.
Any solution that demands more velocity is not your friend.
Greg
Here's my approach.
I trust BC's to within a percent or two. By that I mean the first digit is solid, the second is close to within +/-1 or 2, and the third digit is fantasy.
This is to say that assuming the published number is not poppycock, production variations should match it to within 1% or 2%.
Understand also that BC is not a fixed value, but varies within a range as a product of changing velocity.
Like chrono numbers, BCs are reliable as a comparison; but as an absolute value, not so much.
Any solution that demands more velocity is not your friend.
Greg
Re: BCs and time of flight
Even at 1000 I still hold inside him.
Were you talking about much shorter distances? I think in "normal" hunting type distances, it's a toss up and you use whatever works better on game. By about 6-700 yds., I'd start to look hard at BC's and where the curves cross. Definitely by 1000 I want all the slippery I can get.
John
Even at 1000 I still hold inside him.
Were you talking about much shorter distances? I think in "normal" hunting type distances, it's a toss up and you use whatever works better on game. By about 6-700 yds., I'd start to look hard at BC's and where the curves cross. Definitely by 1000 I want all the slippery I can get.
John
Re: BCs and time of flight
Speed will make the round flatter and drift less closer in (say within 600 yards). But in the long run, the higher BC bullet will provide less wind drift and shoot flatter at distance. I say this with the idea of having the same caliber being used and only switching bullets in that same caliber.
But, it depends on the caliber in question, and what speeds you are able to push each bullet. You would have to look at a ballistic program to see which one would give you the results you would prefer.
Right now, I am debating between a 130 and 140 VLD in my 260 Rem. The 130 grain is much flatter all the way to 1K, but it drifts more in the wind at distance. So, you have to determine which one you would prefer to comprimise.
Speed will make the round flatter and drift less closer in (say within 600 yards). But in the long run, the higher BC bullet will provide less wind drift and shoot flatter at distance. I say this with the idea of having the same caliber being used and only switching bullets in that same caliber.
But, it depends on the caliber in question, and what speeds you are able to push each bullet. You would have to look at a ballistic program to see which one would give you the results you would prefer.
Right now, I am debating between a 130 and 140 VLD in my 260 Rem. The 130 grain is much flatter all the way to 1K, but it drifts more in the wind at distance. So, you have to determine which one you would prefer to comprimise.
Re: BCs and time of flight
I was thinking of the same. I went to the 123 lapuas and haven't seen much of a difference in accuracy. I shot my 284 win using the same theory. It is shooting lights out with a lighter bullet.
Since wind deflection can be a variable in speeds at distances. Would it not help to go the the variable wind differences at a higher velocity. Therefore creating less wind deflection. Using the programs there is very little differences between the wind changes.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Speed will make the round flatter and drift less closer in (say within 600 yards). But in the long run, the higher BC bullet will provide less wind drift and shoot flatter at distance. I say this with the idea of having the same caliber being used and only switching bullets in that same caliber.
But, it depends on the caliber in question, and what speeds you are able to push each bullet. You would have to look at a ballistic program to see which one would give you the results you would prefer.
Right now, I am debating between a 130 and 140 VLD in my 260 Rem. The 130 grain is much flatter all the way to 1K, but it drifts more in the wind at distance. So, you have to determine which one you would prefer to comprimise. </div></div>
I was thinking of the same. I went to the 123 lapuas and haven't seen much of a difference in accuracy. I shot my 284 win using the same theory. It is shooting lights out with a lighter bullet.
Since wind deflection can be a variable in speeds at distances. Would it not help to go the the variable wind differences at a higher velocity. Therefore creating less wind deflection. Using the programs there is very little differences between the wind changes.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Speed will make the round flatter and drift less closer in (say within 600 yards). But in the long run, the higher BC bullet will provide less wind drift and shoot flatter at distance. I say this with the idea of having the same caliber being used and only switching bullets in that same caliber.
But, it depends on the caliber in question, and what speeds you are able to push each bullet. You would have to look at a ballistic program to see which one would give you the results you would prefer.
Right now, I am debating between a 130 and 140 VLD in my 260 Rem. The 130 grain is much flatter all the way to 1K, but it drifts more in the wind at distance. So, you have to determine which one you would prefer to comprimise. </div></div>
Re: BCs and time of flight
The lighter bullet with lower BC will eventually drift more than the slower, higher BC bullet will. It just depends on the caliber and the speeds you're comparing on where the "break even point" will be. For example, if you're looking at a 308 Win comparing a 155 grain to a 190 grain bullet. The 155 will be much flatter, but the 190 will drift less due to higher BC at distance and should have a longer effective range.
But if you're comparing a 7WSM or 7 Mag to a 168 and 180 VLD, the difference between the two is not that much. So, it really depends on the caliber and bullets you are comparing.
The lighter bullet with lower BC will eventually drift more than the slower, higher BC bullet will. It just depends on the caliber and the speeds you're comparing on where the "break even point" will be. For example, if you're looking at a 308 Win comparing a 155 grain to a 190 grain bullet. The 155 will be much flatter, but the 190 will drift less due to higher BC at distance and should have a longer effective range.
But if you're comparing a 7WSM or 7 Mag to a 168 and 180 VLD, the difference between the two is not that much. So, it really depends on the caliber and bullets you are comparing.
Re: BCs and time of flight
I been shooting the 284 with the 168 JLks at 800 yards. I got the 180s but don't know if there would be that much of a difference.
The 155s will shoot flatter. But with the 190 in a 308 to take advantage of the higher bc bullet. It would need to push the bullet a little faster than a 308 to take advantage of the bcs.
Comparison
308 with 155s shooting at 2900 fps at 1000 atli. 1700 10 mph wind at 3
30.5 up and 8.8 wind
308 with 190 shooting at 2600 fps at 1000 same
35.7 8.4
Now you can take that same bullet to a 300wsm and get more advantage out of it.
I been shooting the 284 with the 168 JLks at 800 yards. I got the 180s but don't know if there would be that much of a difference.
The 155s will shoot flatter. But with the 190 in a 308 to take advantage of the higher bc bullet. It would need to push the bullet a little faster than a 308 to take advantage of the bcs.
Comparison
308 with 155s shooting at 2900 fps at 1000 atli. 1700 10 mph wind at 3
30.5 up and 8.8 wind
308 with 190 shooting at 2600 fps at 1000 same
35.7 8.4
Now you can take that same bullet to a 300wsm and get more advantage out of it.
Re: BCs and time of flight
The one thing I haven't take is the bullet weight. Does this help more with the variable wind conditions along the bullet path.
The one thing I haven't take is the bullet weight. Does this help more with the variable wind conditions along the bullet path.
Re: BCs and time of flight
+1 on Litz's book. It has a framework for picking a bullet for a given range. He even has a formula to find a velocity when you move up and down bullet weights.
The way that he does it is to determine the range for which the target is in the "danger zone." In other words, say you pick 1,000 yards and your target is 20". Within what range is your projectile within 10" of your aiming point? For instance, you might have one projectile that is 10" low at 1056 yards and 10" high at 938 yards. The danger zone in that case is 1056 - 938 or 118 yards (that is obviously not a real world example, but you get the point).
The beauty of Litz's book is that he provides BC's for various brands and models of bullets, so you don't have to rely on manufacturers' numbers, which can be inflated, but which are not uniformly inflated across all manufacturers.
+1 on Litz's book. It has a framework for picking a bullet for a given range. He even has a formula to find a velocity when you move up and down bullet weights.
The way that he does it is to determine the range for which the target is in the "danger zone." In other words, say you pick 1,000 yards and your target is 20". Within what range is your projectile within 10" of your aiming point? For instance, you might have one projectile that is 10" low at 1056 yards and 10" high at 938 yards. The danger zone in that case is 1056 - 938 or 118 yards (that is obviously not a real world example, but you get the point).
The beauty of Litz's book is that he provides BC's for various brands and models of bullets, so you don't have to rely on manufacturers' numbers, which can be inflated, but which are not uniformly inflated across all manufacturers.
Re: BCs and time of flight
I don't mean to step on anybody's shoes. I know Litz's book is well received.
But I kinda go off of the bullet manufactures listed BC. I shot Lapuas mostly in my 308s and 260s. Their numbers have worked for me. I would think that Lapua may have done some research on BCs. I do think Lapua uses doppler for their bcs. This is just my thinking.
I was mostly interested in real world knowledge of actual shooting experience not what a book tells everybody.
Sometime ago a fellow hide member was telling me to shoot the 123s over the 139s out to 1000. At that time I was a little closed minded on thinking higher BC is better. Since then, I have loaded up the 123s and have good results with them. Then tried this with the .284 win. with the 168 JLKs and had great results with this.
I don't mean to step on anybody's shoes. I know Litz's book is well received.
But I kinda go off of the bullet manufactures listed BC. I shot Lapuas mostly in my 308s and 260s. Their numbers have worked for me. I would think that Lapua may have done some research on BCs. I do think Lapua uses doppler for their bcs. This is just my thinking.
I was mostly interested in real world knowledge of actual shooting experience not what a book tells everybody.
Sometime ago a fellow hide member was telling me to shoot the 123s over the 139s out to 1000. At that time I was a little closed minded on thinking higher BC is better. Since then, I have loaded up the 123s and have good results with them. Then tried this with the .284 win. with the 168 JLKs and had great results with this.
Re: BCs and time of flight
Run the numbers comparing 2 bullets that are part of my question. Alt. 1700
The 139s running at 2800 to 2850 this a fair number for this out of a 260.
Then run the numbers on a 123 lapua running at 3000 to 3050 out of a 260.
The 139s (2850fps) come ups is roughly 27.3 moa and wind 6.5 moa (10 mph at 3) time of flight 1.442
The 123s come ups is roughly (3000fps) 24.7 and wind 6.5 same conditions time of flight 1.385
Run the numbers comparing 2 bullets that are part of my question. Alt. 1700
The 139s running at 2800 to 2850 this a fair number for this out of a 260.
Then run the numbers on a 123 lapua running at 3000 to 3050 out of a 260.
The 139s (2850fps) come ups is roughly 27.3 moa and wind 6.5 moa (10 mph at 3) time of flight 1.442
The 123s come ups is roughly (3000fps) 24.7 and wind 6.5 same conditions time of flight 1.385
Re: BCs and time of flight
I look at BC's and I look at the weight and the cartridge its coming out of.
For example looking at the 155 scenar and the 175 smk. Results will be similar at the 155 has a high BC but shoots faster. Its light weight means it bucks the wind less.
The 175 has a good BC as well and shoots slower, but is slightly heaver so bucks the wind better than the 155..
Then you have the 240... massive bc but will shoot slow as hell out of a .308.
So what im saying in all of this is that the Bigger the BC the better and the more weight the better in bucking the wind... but you often sacrifice speed with the heavies.
The solution is to shoot magnums so you can push those heavies with massive BC's extremely fast.
The downside is recoil and barrel life.
I look at BC's and I look at the weight and the cartridge its coming out of.
For example looking at the 155 scenar and the 175 smk. Results will be similar at the 155 has a high BC but shoots faster. Its light weight means it bucks the wind less.
The 175 has a good BC as well and shoots slower, but is slightly heaver so bucks the wind better than the 155..
Then you have the 240... massive bc but will shoot slow as hell out of a .308.
So what im saying in all of this is that the Bigger the BC the better and the more weight the better in bucking the wind... but you often sacrifice speed with the heavies.
The solution is to shoot magnums so you can push those heavies with massive BC's extremely fast.
The downside is recoil and barrel life.
Re: BCs and time of flight
Dar, take your same example of heavy vs light and compare the Litz BCs of the Berger 155.5 Fullbore bullet and the 208g Amax. I did the calcs on the Berger starting at 2950 fps and the Amax at 2500 fps.
Elevation MOA from 100 yard zero with 155.5g 600 yards to 1000 yards:
12.4, 16.1, 20.4, 25.2, 30.7
Elevation for 208 Amax
16.3, 20.7, 25.5, 30.9, 36.8
Wind drift for 155.5, 10mph cross wind at 3 oclock:
4.4, 5.4, 6.5, 7.6, 8.9
Wind drift for 208g Amax:
3.9, 4.7, 5.6, 6.5, 7.5
I worry about wind drift, so if I could tolerate the recoil, I would rather shoot the Amax over the Berger.
Dar, take your same example of heavy vs light and compare the Litz BCs of the Berger 155.5 Fullbore bullet and the 208g Amax. I did the calcs on the Berger starting at 2950 fps and the Amax at 2500 fps.
Elevation MOA from 100 yard zero with 155.5g 600 yards to 1000 yards:
12.4, 16.1, 20.4, 25.2, 30.7
Elevation for 208 Amax
16.3, 20.7, 25.5, 30.9, 36.8
Wind drift for 155.5, 10mph cross wind at 3 oclock:
4.4, 5.4, 6.5, 7.6, 8.9
Wind drift for 208g Amax:
3.9, 4.7, 5.6, 6.5, 7.5
I worry about wind drift, so if I could tolerate the recoil, I would rather shoot the Amax over the Berger.
Re: BCs and time of flight
The essence of this analysis is to consider what the greatest uncertainty is in your particular shooting application.
If you use a laser rangefinder, and always know the range to the target, there's no advantage to a 'flat' shooting round. The biggest uncertainty in your shooting will be wind effects. In this case, the heavy bullet is better for you because it's best at minimizing wind deflection.
However, if you do a lot of shooting where you don't know the range to the target, then the 'flatter' trajectory has an advantage because it allows you to hit your target even if you don't know the precise range. Keep in mind that the lighter, flatter bullet will usually have more wind deflection though.
There is no 'best' answer for everyone here, otherwise there would only be one bullet weight made. It's a trade-off. Consider which option is better suited to the type of shooting you usually do, and the predominant uncertainties involved. Then make an informed decision based on that.
-Bryan
The essence of this analysis is to consider what the greatest uncertainty is in your particular shooting application.
If you use a laser rangefinder, and always know the range to the target, there's no advantage to a 'flat' shooting round. The biggest uncertainty in your shooting will be wind effects. In this case, the heavy bullet is better for you because it's best at minimizing wind deflection.
However, if you do a lot of shooting where you don't know the range to the target, then the 'flatter' trajectory has an advantage because it allows you to hit your target even if you don't know the precise range. Keep in mind that the lighter, flatter bullet will usually have more wind deflection though.
There is no 'best' answer for everyone here, otherwise there would only be one bullet weight made. It's a trade-off. Consider which option is better suited to the type of shooting you usually do, and the predominant uncertainties involved. Then make an informed decision based on that.
-Bryan
Re: BCs and time of flight
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dar</div><div class="ubbcode-body">
I was mostly interested in real world knowledge of actual shooting experience not what a book tells everybody.
</div></div>
So let me get this straight... rather than believing a published book written by a professional and degreed ballistician, you want to ask the Internet?
Sorry, I had to give you some sh!t on that one!
But seriously, if you have these kinds of questions, buy Litz's book. It has lots of valuable tools in there such as the danger zone calculation I showed above. You can also figure out what velocity you will achieve at the same pressure for a different weight of bullet, for comparison's sake.
It just has tons of useful info in there for shooters like us (and by us, I mean broadly, long range, F-class, tactical, and long distance hunters that frequent this site). I should talk... I put off buying the book for a long time. But for the price of a box of bullets or a couple of boxes of ammo you get invaluable information.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dar</div><div class="ubbcode-body">
I was mostly interested in real world knowledge of actual shooting experience not what a book tells everybody.
</div></div>
So let me get this straight... rather than believing a published book written by a professional and degreed ballistician, you want to ask the Internet?
Sorry, I had to give you some sh!t on that one!
But seriously, if you have these kinds of questions, buy Litz's book. It has lots of valuable tools in there such as the danger zone calculation I showed above. You can also figure out what velocity you will achieve at the same pressure for a different weight of bullet, for comparison's sake.
It just has tons of useful info in there for shooters like us (and by us, I mean broadly, long range, F-class, tactical, and long distance hunters that frequent this site). I should talk... I put off buying the book for a long time. But for the price of a box of bullets or a couple of boxes of ammo you get invaluable information.
Re: BCs and time of flight
Bryans book is awesome if you like to read up on the nitty gritty for our hobby. I rate it highly as one of the most useful resources I have available on my bookshelf.
Bryans book is awesome if you like to read up on the nitty gritty for our hobby. I rate it highly as one of the most useful resources I have available on my bookshelf.
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