nralifer
Well-Known Member
Thank you.
Bullet Construction vs Lethality
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Have unfortunately not had the chance to read any of Litz's material, but these formulas are approximations typically used by engineers where it isn't possible to take all the variables into account in real world situations. So, some ramblings for your entertainment only:
For starters, a projectile doesn't suddenly achieve crosswind speed (the component of wind velocity at 90 degrees to the direction of travel) instantly. It has a mass and is accelerated by the wind: v=at, a=f/m. The force f is related to the sectional density and form factor of the projectile at 90 degrees to the path of the projectile. Simply put, the wind is pushing against the side of the bullet, which has a much lower sectional density than the front of the bullet, and a different form factor. Another thing to consider is that parasitic drag (as opposed to induced drag) is proportional to the square of the wind speed. This 'drag' is the force acting to accelerate the projectile 'sideways' in a crosswind. In a steady wind, the projectile probably achieves crosswind speed fairly quickly, who knows? But in variable crosswinds there could be significant effects. Obviously the form factor is influenced by the rifling marks, probably less so in a 'borerider' bullet.
Now most of this goes out the window when you consider that the projectile is going at supersonic speeds, and there is a big shock wave disturbing the airflow.
BTW, the BC of a bullet is it's sectional density divided by its form factor, whether it be G1 or G7 frontal form factor or the 90 degree form factor.
Edit: Just to clarify, wind drift is proportional to crosswind velocity once the bullet reaches crosswind velocity. The above discussion is related to how long the bullet takes to achieve crosswind velocity, particularly in variable winds downrange.
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These formulas are what ballistic calculators use, as well as other formulas related to other environmental conditions, spin drift, coriolos, etc. if you use a ballistic calculator, to include a Kestrel with ballistic software, you're getting a firing solution with these formulas.
BC relates to ToF and lag time. That's how it affects wind drift. I've already stated wind is not constant and when you input a value it's not going to be accurate if that value changes, and it almost always does.
There's so much more that can be said and added to clarify and correct things, but I'm not going to bother in this thread. For one, that's not the point of the thread, and two, it's obvious some just want to be more right. So I'm not going to keep going just as an exercise in futility. A new thread could maybe be worth it though.
Less than 10 minutes ago I would have agreed with you. Then I found this article from Litz (can't afford his books) stating two things:
When it comes to long range target shooting, wind deflection is the most important factor of external ballistic
performance.
In Table 1, I've shown the velocities required for each bullet to match the wind deflection of the benchmark. What may not be clear is that it is easier to achieve those velocities with the larger calibers than the small ones.
To be fair, this is for target shooting at a known range, so a flat trajectory would still be very important for hunting situations - unless you have time to get a range and adjust for it. Although at 1000 yards, you had better get a range and adjust for it or you are going to miss. He talks about recoil, but in my case at least - elk hunting - recoil is a fact of life.
So this does, in fact, have to do with the original post: Bullet Construction for Long Range Lethality - make the diameter larger.
Understanding Long Range Bullets - Litz
What aren't you agreeing with? I think perhaps you misunderstood/misinterpreted that article because it's saying the same things I did.
"Understanding Wind Deflection
One way to think about wind deflection is in terms of 'lag time'. Lag time is the difference between the vacuum time of flight, and the actual time of flight.
For example, say you shoot at a target 1000 yards away with a bullet of initial speed 3000 fps. The vacuum time of flight is 1.00 second (3000 feet at 3000 feet per second). Due to atmospheric drag slowing the bullet down, the actual time of flight may be closer to 1.6 seconds. In this case, the lag time is 0.6 seconds. From here, calculating the wind deflection is easy. Just multiply the lag time by the cross- wind speed, being careful of units. Lets say there was a 10 mph (14.66 fps) crosswind for the 1000 yards of bullet flight. 14.66 fps X 0.6 seconds = 8.8 ft, or 105 inches. The hard part in all of this is figuring out the actual lag time. It depends on actual time of flight, which depends on BC.
Bullets with higher BC's will always have less lag time when fired at the same velocity. The question is, how much velocity can you give up with a higher BC bullet, and still have less lag time? We can get a rough idea about this from looking at Table 1. As a general rule, you can go about 496 fps slower for every +0.100 counts of BC, and match wind deflection. For example, our benchmark 142 gr bullet going 2950 fps (BC = .565) has 70 inches of wind deflection in a 10 mph crosswind at 1000 yards. What speed does a heavier bullet having a BC of 0.5964 need to match the wind drift of the benchmark? Well, there's 0.031 difference between the BC's, so .31 x 496 fps = 154 fps. So a bullet with a BC of 0.596 only needs to have a muzzle velocity of 2950 fps – 154 fps = 2796 fps in order to match the wind deflection of the lighter faster benchmark. This compares well with the 2800 fps in Table 1."
He also says this:
"BC Advantage of the Larger Calibers
In Table 1, I've shown the velocities required for each bullet to match the wind deflection of the benchmark. What may not be clear is that it is easier to achieve those velocities with the larger calibers than the small ones. For example, the little 90 gr .224 bullet has to get to 3270 fps. That's not easy. Excessive pressure, accelerated barrel wear, and possible bullet failure happen at this kind of speed. The 2950 fps of the benchmark is a 'stout' velocity for the 6.5-284. 2800 fps in the 7mm can be done with the same case and powder as the 6.5-284. I don't want to get into a discussion about case volume and powder efficiency here because I'm frankly not that knowledgeable about it. Besides, this is about external ballistics, not internal. What I can say is that it's easier to achieve 2650 fps with a number of .30 caliber chamberings and 220 grain bullets than it is to achieve 3270 fps with .224 chamberings. That means that there is more potential to beat the benchmark 70" of wind drift by going to a larger caliber, rather than smaller.
Of course, driving the heavy bullets at higher speeds results in less wind deflection, but you may run into the same problems that the smaller calibers have like high pressure and short barrel life. Not to mention the crippling recoil! Fast heavy bullets are best suited for heavy benchrest rifles that can absorb the recoil. I know only a few people who can successfully manage the recoil of a 30-338 prone rifle. Those who handle the recoil definitely have an edge in the wind. Be honest with yourself about your recoil comfort level before you decide to go with such a monster."
What he's saying is in the table he made, the smaller caliber bullets have to be at a much higher velocity to get the same wind drift amount. It's harder to push those bullets to those velocities versus the heavier bullets in bigger cartridges. It's not impossible, obviously, but it takes more uncommon steps to achieve. Larger calibers tend to get the same drift, slower, meaning they're more efficient. It still will depend greatly on the particular bullet and it's shape and design.
And yes, talking about BC, wind drift potential, etc does have to do with bullet construction and affects ability to put the bullet on or as close to POA as possible. Being able to do that or not affects lethality.
What I was saying wasn't the intent of this thread is arguing about if BC affects wind drift, accuracy of formulas or their existence, etc.
If you want to keep discussing how a bullet with more BC and less negative affect from the wind, and how that can help with its lethality in the form of making it easier and more capable of hitting your mark, especially up to the 1000 yard mark as mentioned in the OP, I'm quite alright continuing that discussion.
I completely agree that if a bullet for hunting doesn't perform worth a darn terminally, it doesn't matter how accurate it is to hitting its mark. It could be the highest BC bullet you can shoot, but if it doesn't perform well terminally, it's junk as far as I'm concerned, for hunting. Conversely, a bullet may perform extremely well terminally, but if it's unreliable at hitting its mark due to low BC and being pushed all over by the wind, inconsistencies in construction and balance, etc, then its terminal performance doesn't really matter so much. You have to hit the animal first, and hit it in the vitals in particular.
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You have been discussing it for about 20 pages or so now so why stop now
stealing this
Because people like you seem to have issue with it
. And I'm only trying to discuss the points that actually matter to the thread. Care to add anything productive to the discussion? Are you just here to interject?
Yeah Petey I would, back some 10 pages ago where you compared a 215 Berger against a 124 solid you stated that the the 215 was the clear winner@ a K so my question is did you actually verify this on the range at distance and have you verified any of the information you have been providing or just looking at it on paper just like the rest of us can do with any of the ballistic software available, furthermore the 124g bullet in question is not a 1000 yard bullet and was never considered for that distance, the 124 is an 800 yard setup per the velocity bracketsBecause people like you seem to have issue with it
Care to add anything productive to the discussion? Are you just here to interject?
Only 4 pages ago.
I didn't say it was the clear winner. I used it comparison because you alluded to it and I also compared them at 500 yards, not just 1000.
I'm pretty sure I just gave stats. Perhaps you concluded it was the clear winner from that?
I gave an example with particular specs. That's all it was. I never said the 124gr HH is a 1000 yard hunting bullet. That was not the thing in question.
I have not shot both bullets at those exact specs side by side to verify it, but I don't need to to prove the specific point I was making. I have shot many bullets and cartridges to many distances to have the confidence and experience to back up what I've said. And what I've said is how the math and physics work in relation to reality. I mentioned how there are many other factors and variables that affect the actual point of impact. I have experienced that plenty. It never made me question if BC doesn't affect wind drift.
If you think I need to go shoot both bullets side by side as the only way to prove anything, you're only saying that because you want it (me) to be wrong. The test done in the video linked in the thread shared earlier, for example, didn't show us much. It showed dust splashing around the same area at 876 yards. At the MVs given for both loads, and even in a 10mph full value (constant) wind, there would only be a 2" difference in drift using advertised BCs. We can't see that on the video, and with only dust flying. Cody and Adam had similar things to say in that thread.
Honestly, you can chose not to believe what I say and act like I don't know what I'm talking about. I don't care. You can challenge my experience all you want. I don't post everything I do or have done, for a reason. Proving myself to people does not concern me.
My experience 100% aligns with things AB has published. I've yet to be able to prove anything otherwise.
What you said boils down still to just an interjection. What was productive by it?
Sounding a little combative, brothers. 
Some folks come across like they're riding the high horse of facts and others don't sit so well by it. Human nature. Sometimes "facts" get bent a little in real life for inexplicable reasons. LOL
Some folks come across like they're riding the high horse of facts and others don't sit so well by it. Human nature. Sometimes "facts" get bent a little in real life for inexplicable reasons. LOL
Just defensive on this side, and I wish I didn't feel the need to be. No horse over here, high or otherwise. Facts can get pesky though.Sounding a little combative, brothers.
memtb
Well-Known Member
Facts…..obviously interpreted differently by different people! memtb
Yep. And it depends on what we're calling facts. I get pretty particular on what I call a fact.
