Federal New Cartridge

[BBob]

When I punch a large SD into a WEZ calculator the hit probability goes to crap at distance. If large velocity variations are not indicative of some amount of vertical stringing...
I mean how would that be? If you're somehow perfectly zero'd at X distance at X velocity, and then the velocity drops 50fps, physics would require that shot to hit somewhere lower than the previous that was at the X velocity.

Your thinking is too narrow. You are only taking a few variables and plugging them into a calculator, not the whole system as it works in the world. Some things still cannot be totally explained by rigid math. Just because you think it's fully logical doesn't mean it is, it might mean you're missing something.

Peruse this dilemma by researching how many long range BR folks these days get better winning groups with a larger ES/SD than smaller. It is really common. Positive compensation has been suggested as a reason. It hasn't been proven but it's a theory. The single digit ES holy grail isn't what it was cracked up to be.

 

[Dos XX]

I've never shot a load with an es over 20 in competition, but I have chosen a load with an es of 16 or 17 over one with an es of 9 because it shot smaller at 1000 yds. I also won some medals with it.

I'm not saying one with es over 20 can't do it. I'm just saying I haven't personally seen one in my experiences. If I do, I will shoot it, though.

 

[BBob]

One example from a well known 1K shooter/gun builder:

"My point is guys will get on a ballistics calculator and say you need x es to shoot x vertical based on bullet drop. They ignore barrel harmonics. Theres 12 shots in 3.6 inches of vertical at 1k with 36 fps of es. 9 shots in 2 inches with 23. They will tell you that's not possible. It's very common to see if you shoot groups a lot. I try to help guys improve their accuracy and so many are focused on single digit es when they are shooting .5 moa or bigger. I dont want to hear about single digit es unless your shooting under an inch at 1k or your shooting past a mile."

Keeping it simple with reloading

More than one way to skin a cat. As long as your rounds are consistent you're doing it right IMHO. Of course what do I know. I use Lemon pledge!! LOL.

www.longrangehunting.com

 

[z987k]

Your thinking is too narrow. You are only taking a few variables and plugging them into a calculator, not the whole system as it works in the world. Some things still cannot be totally explained by rigid math. Just because you think it's fully logical doesn't mean it is, it might mean you're missing something.

Peruse this dilemma by researching how many long range BR folks these days get better winning groups with a larger ES/SD than smaller. It is really common. Positive compensation has been suggested as a reason. It hasn't been proven but it's a theory. The single digit ES holy grail isn't what it was cracked up to be.

The only way the same rifle and bullet are not shooting lower with something like 50fps less is if it's being compensated for. Physics is physics. Something slower with the same drag profile has to be lower. Something faster has to be higher.
Random dispersion due to barrel harmonics and the shooter(the largest variable) can eat into that, but if we assume a hard mounted rifle that cannot change it's point of aim, there's no way you're not going to see it drop.
I would expect the same result if I dropped the powder charge and got lower velocity. Let's take this thought experiment to it's extreme. My ES is 400fps. First shot is 2800fps. Then next is 2400fps. Then next is 2600. That's not going to have vertical stringing?

I generally don't chase SD, but I also don't hunt at ranges where larger SD's would mean I miss.

 

[Axlrod]

The only way the same rifle and bullet are not shooting lower with something like 50fps less is if it's being compensated for. Physics is physics. Something slower with the same drag profile has to be lower. Something faster has to be higher.
Random dispersion due to barrel harmonics and the shooter(the largest variable) can eat into that, but if we assume a hard mounted rifle that cannot change it's point of aim, there's no way you're not going to see it drop.
I would expect the same result if I dropped the powder charge and got lower velocity. Let's take this thought experiment to it's extreme. My ES is 400fps. First shot is 2800fps. Then next is 2400fps. Then next is 2600. That's not going to have vertical stringing?

I generally don't chase SD, but I also don't hunt at ranges where larger SD's would mean I miss.

Thought experiments are not real world, and neither is 400 fps ES. The only thing that matters is the target.

I shoot at the range, where a few 1000 yd BR guys tune, that is in @BBob's post. This is where I picked up my load development method. Those guys choose the load for target and hunting guns based on vertical , not ES.

This is from that thread post #152, it's Wheeler on ES at long range. This is stuff you can test with your own gun, without believing someone on the internet though.

Literally hundreds if not 1000s of 1000yd groups and what I posted is just what I expect to see. Its very rare to shoot the little groups with small es. The small es groups usually have too much vertical. The single digit group thats tiny at 1k is kind of rare. Dont ask me exactly why it works out this way but it does. I dont think theres anyone out there that posts as many 1000yd groups as I do. And I only post a fraction of what I shoot. Theres guys that shoot more of them then me that do not post online. We all share this stuff with each other. The data base is huge spanning well over 10 years. Its just that not many guys are doing this stuff so it seems to go against the grain of theory.

 

[solarshooter]

It is incorrect to believe that Velocity ES and SD directly correlates with vertical or group size at distance.

I believe what Form is trying to say here is that MV dispersion is only one of many variables (rifle accuracy error, aiming error, BC error, wind error, etc) that affect point of impact on target. If you disperse this effect with realistic variations on those other effects, you will not see a 1:1 change in vertical.

When I punch a large SD into a WEZ calculator the hit probability goes to crap at distance. If large velocity variations are not indicative of some amount of vertical stringing...
I mean how would that be? If you're somehow perfectly zero'd at X distance at X velocity, and then the velocity drops 50fps, physics would require that shot to hit somewhere lower than the previous that was at the X velocity.

Now that being said, a lot of people are using ES and SD interchangeably in this thread. It's very important to understand that SD has roughly 3x the effect of ES. So talking about a 30fps SD or a 30fps ES are two drastically different things - that would be like saying 90fps ES vs 30fps ES. I absolutely believe that increase an MV SD from say 10fps to 30fps will have a significant effect on hit rates at 500+yds. Perhaps you could post some WEZ runs to quantify this.

Positive compensation is an interesting theory, and Bryan Litz did some testing of it in his latest book. His conclusions were not definitive either way, but they certainly did not disprove the theory. Now, as is well known around here I am very skeptical of "anecdotes as evidence". The testimonies from the BR shooters are extremely vulnerable to small sample testing errors, confirmation bias, and many other pitfalls in data interpretation that that community is particularly prone to. Do I believe that small groups have been shot with greater than single digit MV SD? Yes. Is this proof of positive compensation? No. There are many, many other explanations for these small groups.

 

[Okie_Poke]

I should stay out of this as I'm just an armchair long-range shooter for the most part. But this is the internet, and I've read some books, blogs, and forums, so here we go.

I believe what Form is trying to say here is that MV dispersion is only one of many variables (rifle accuracy error, aiming error, BC error, wind error, etc) that affect point of impact on target. If you disperse this effect with realistic variations on those other effects, you will not see a 1:1 change in vertical.

This makes sense to me. The statement that ES and SD don't "directly correlate" with vertical dispersion at long range left me scratching my head a little bit. It seems obvious/logical that they are correlated and that vertical dispersion at range is a function of muzzle velocity consistency.

Here's a snippet from Litz making the point that muzzle velocity consistency can be more important to long range hit probability than raw dispersion in certain circumstances.




Shamelessly snipped from: https://www.facebook.com/BryanLitzB...may-be-frustrated-getting-co/505306375445571/

But I agree it's not 1:1, and there is a point of diminishing returns to muzzle velocity consistency. Where that point is will depend on several other variables including those listed and the target size.

Here's an example from Cal based on WEZ:



From: https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/

Now that being said, a lot of people are using ES and SD interchangeably in this thread. It's very important to understand that SD has roughly 3x the effect of ES. So talking about a 30fps SD or a 30fps ES are two drastically different things - that would be like saying 90fps ES vs 30fps ES. I absolutely believe that increase an MV SD from say 10fps to 30fps will have a significant effect on hit rates at 500+yds. Perhaps you could post some WEZ runs to quantify this.

Agree with all of this. To bring this back to what started our sidequest here:

My experience with these really high performing ball powders... like leverevolution or superformance is that you will NEVER get the ES/SD needed for ethical shots at 800, let alone 1000 yards. They're great for speed, but not consistent enough for that long of range of shooting. Which mirrors what the Allterra guys were seeing.
My reloads for the 277 fury, the best SD I have for that round at higher pressures is 37(sample size 52). Run that through a WEZ and tell me you're taking a shot at even 500 yards. If I back the pressure off and use a single base stick at just over 65k, I can get great SD's around 5.

An SD of 37 based on that many shots translates to an ES of something like 110 from fastest to slowest. Assuming a 110 fps difference and using Federal's published G1 BC for the 170 TA (.646) and 3000 fps as a mid-point (so a velocity range of 2945 - 3055), velocity variability is contributing up to 3.61"/0.68MOA/0.2MIL of vertical dispersion at 500 yards. That's not a miss on big game all by itself, but it's not all by itself and it's only going to get worse the further you go out. I don't have access to the WEZ tool, but as solarshooter said, it would be interestng to see how much that affects hit probability under various scenarios at 500 yards (and further ranges).

z987k : did you run a WEZ analysis on this that you could share?

Positive compensation is an interesting theory, and Bryan Litz did some testing of it in his latest book. His conclusions were not definitive either way, but they certainly did not disprove the theory. Now, as is well known around here I am very skeptical of "anecdotes as evidence". The testimonies from the BR shooters are extremely vulnerable to small sample testing errors, confirmation bias, and many other pitfalls in data interpretation that that community is particularly prone to. Do I believe that small groups have been shot with greater than single digit MV SD? Yes. Is this proof of positive compensation? No. There are many, many other explanations for these small groups.

Agree again. Count me among the skeptics.