Velocity and accuracy?

[murf]

So faster is always more accurate, according to you.

Do you have the data to support that? And how did you test it?

yes, it's always more accurate in my hypothetical scenario.

murf

 

[murf]

Now you're saying there is no correlation? It's immeasurable?

there is correlation in my "trajectory" example. my logic may be off, but i don't think so.

murf

 

[fxvr5]

there is correlation in my "trajectory" example. my logic may be off, but i don't think so.

murf

But it's a completely arbitrary example with a forgone conclusion. Change a few numbers around and you get a different result.

 

[murf]

But it's a completely arbitrary example with a forgone conclusion. Change a few numbers around and you get a different result.

change numbers around in most anything and one will get a different result. the example is very specific and germane to the op, not arbitrary. my example has a predictable result because it is a simple mathematical formula.

if the logic is not sound, then let me know why.

murf

 

[fxvr5]

change numbers around in most anything and one will get a different result. the example is very specific and germane to the op, not arbitrary. my example has a predictable result because it is a simple mathematical formula.

if the logic is not sound, then let me know why.

murf

The logic is fine. But that's not what counts. It doesn't mean the real world will fit your example. But it's a testable hypothesis. Try it and tell us about your methods and results.

 

[ATLDave]

ok, lets say you shoot ten shots @ 1,000 fps and ten shots @ 1,500 fps (same gun, same bullet). both loads have an extreme spread of 15 fps. the higher velocity round will show less variation in trajectories than the slower round (extreme spread/muzzle velocity is 1.5% for the slower round and 1% for the faster round). so the higher velocity round will show a smaller group size. make sense?

You are assuming that variation in velocity is the driver of group size in handguns. It isn't. There has been research on this point.

As to your core position that "faster = more accurate for hand-held handgun shooting*, we already know that is incorrect. We know it because bullseye competitors and other purely accuracy/precision-oriented shooters do not load supersonic rounds. Competition between sophisticated competitors serves as an extremely efficient laboratory. For something as straightforward as testing whether more velocity = smaller groups, it's a pretty good bet that a roughly a century's worth of testing would have identified any such dynamic.

As to why, there are a bunch of reasons. But there's not really a big question as to whether there is a direct connection. We already know the answer to that.

*If one is talking about "handgun" shooting where people are using rifle bullets fired from guns that are bagged/bipoded at targets 100 meters or more away, you start to get into areas where speed helps avoid wind-drift or reduce the effect of ranging uncertainties. That positive function of speed has nothing to do with inherent precision, but with reducing uncertainties in environmental conditions. I don't think this is the kind of shooting the OP was asking about, but, if he was, then that is a separate discussion.

 

[murf]

There has been research on this point.

sources? i don't believe there is evidence of this as the variables are too many to isolate velocity and accuracy. on a theoretical basis, and knowing velocity always varies with each shot, an increase in velocity will reduce the vertical spread of the group (and thus accuracy) assuming the velocity variations at the two velocities is the same (based on flatter trajectories of faster bullets).

one could plug the extreme velocity values of each load in a balistics program and see the change in point of impact. the distance would have to be hundreds of yards to see a difference, but the concept applies at all velocities.

murf

 

[murf]

You are assuming that variation in velocity is the driver of group size in handguns.

no, i don't. delta velocity is not a driver, just one variable.

murf

 

[murf]

You are assuming that variation in velocity is the driver of group size in handguns. It isn't. There has been research on this point.

As to your core position that "faster = more accurate for hand-held handgun shooting*, we already know that is incorrect. We know it because bullseye competitors and other purely accuracy/precision-oriented shooters do not load supersonic rounds. Competition between sophisticated competitors serves as an extremely efficient laboratory. For something as straightforward as testing whether more velocity = smaller groups, it's a pretty good bet that a roughly a century's worth of testing would have identified any such dynamic.

As to why, there are a bunch of reasons. But there's not really a big question as to whether there is a direct connection. We already know the answer to that.

*If one is talking about "handgun" shooting where people are using rifle bullets fired from guns that are bagged/bipoded at targets 100 meters or more away, you start to get into areas where speed helps avoid wind-drift or reduce the effect of ranging uncertainties. That positive function of speed has nothing to do with inherent precision, but with reducing uncertainties in environmental conditions. I don't think this is the kind of shooting the OP was asking about, but, if he was, then that is a separate discussion.

thanks for your response. i'm still sticking to my guns.

murf

 

[murf]

The logic is fine. But that's not what counts. It doesn't mean the real world will fit your example. But it's a testable hypothesis. Try it and tell us about your methods and results.

no, it is not testable. there are too many variables to account for to get a meaningful outcome. environment, recoil, powder combustion, bullet weight and balance, etc.

the difference would be small, in my opinion, but is there non the less. whether this is relevant to handgun shooting is moot. the op asked and i answered.

thanks for your input on the logic part.

murf

 

[fxvr5]

no, it is not testable. there are too many variables to account for to get a meaningful outcome. environment, recoil, powder combustion, bullet weight and balance, etc.

the difference would be small, in my opinion, but is there non the less. whether this is relevant to handgun shooting is moot. the op asked and i answered.

thanks for your input on the logic part.

murf

It is testable. As to other variables, either they can be measured and sorted/controlled for, or one can assume, for the purposes of the experiment, that they will be equal for all conditions. This is done all the time. Then you run the test and see what you get. If changes in conditions/variables are felt needed, you make the changes and run it again. But you'll never get an answer if you're too afraid of running the test.

 

[murf]

It is testable. As to other variables, either they can be measured and sorted/controlled for, or one can assume, for the purposes of the experiment, that they will be equal for all conditions. This is done all the time. Then you run the test and see what you get. If changes in conditions/variables are felt needed, you make the changes and run it again. But you'll never get an answer if you're too afraid of running the test.

no sense to assume variables as constants and expect accurate results. if this is done all the time, then you can provide an example of how it is done. any reference will do.

murf

 

[fxvr5]

Minor variation in everything is normal, and we can’t control most of it.

With respect to testing accuracy, you can exercise some control in how you design the test. Use components from the same lot number. i.e. primers from the same lot number, bullets from the same lot number, powder from the same lot number, brass from the same lot number - trim to the same length if you want - and so on.

The best method would be to take the barrel from the gun and put it in a barrel holding device. This eliminates human error and tolerances in gun parts fitting that could increase error.

With any experiment, you control the things you can and assume that variation in things you can’t control will be equal for all different conditions. There will be minor variation in the exact brisance of every primer, difference in the exact pressure and velocity from every round fired, difference in the exact weight and concentricity of the bullets, and so on. Shoot enough shots so that you have confidence in the results, repeat, perhaps several times, to reduce the chance of type I and type II errors, then see what the data says.

It’s not that hard.

 

[ATLDave]

Either this is a detectable phenomenon or it is not a thing. Given a large enough sample size, relatively small-but-real differences should be able to be teased out. If one tries several different setups and accumulates large samples and the effects do not materialize, then the reasonable conclusion is that the thing does not exist, or at least does not exist in any practical way.

This is pretty much what happened with the baseball statistical search for the clutch hitter. Some of the earliest advanced statistical efforts went into testing for the existence of clutch hitters - i.e., someone whose past performance in some circumstances defined as "clutch" was predictive of future "clutch" performance. Fortunately, MLB provides vast sample sizes (162 games per team per year yields a heck of a lot of trials). And in analyzing that vast data set over many, many years of experiments (as each at-bat might be considered), no clutch hitters appeared. Unlike, say, home runs, a hitter's relatively performance " in the clutch" in the prior year didn't predict whether they would perform better or worse than their baseline "in the clutch" next year. Clutch hits exist - anything that happens in the clutch is clutch. But clutch hitters do not. Teams that accepted this got an advantage, as they no longer overpaid for supposedly-clutch hitters during free agency. They paid for the aspects of overall performance that were predictive of future performance.

Similarly, someone interested in loading for accuracy in handguns should pay attention to the things that matter, and not chase dimensions of performance that are so ephemeral they cannot even be tested.

 

[murf]

thanks guys. i'm going to "exit stage right" here. the question has been answered satisfactorily, i think.

murf

 

[Varminterror]

What we know, from decades on decades of competitive shooting with handguns:

• Longer barrels in handguns are fired more accurately, on average, than shorter barrels.

• Faster lock times improve precision.

• Solid backwalls on triggers, and proper trigger follow through techniques to hold against the back wall during the shot improve precision.

• Being mindful of transonic transition range against muzzle velocity can improve precision in handgun games (also in rimfire rifle games, less applicable in centerfire rifle games, naturally).

So real world results would confirm that the shooter CAN AND DOES influence the firearm enough during nearly-zero time spans to affect their groups. Lest a shorter lock time would not be an advantage, nor would be trigger stops or follow through techniques. BUT the advantages of longer barrels, despite their longer dwell times are more shootable than shorter barrels, AND purely sub-sonic ammunition which avoids transonic transition within the sporting distance, also increasing dwell time, improves precision. So yes, a shooter can influence the bullet during the dwell time, but a plethora of other factors also influence precision sufficiently to outweigh the importance of shortened dwell time.

Personally, if I find a bullet and powder combination which is terribly sensitive to velocity changes - meaning terribly sensitive to powder charge changes - then “that dog don’t hunt.” Searching for a forgiving charge weight envelope to ensure consistency is ALWAYS a major objective for my reloading. If a tenth of a grain of powder means a 30fps shift, and makes or breaks my precision, I’m scrapping the whole project, regardless of how well the “made” load shoots.

 

[gwpercle]

In my 50 years of reloading, mostly handgun ammo , I have discovered that my best pistol loads , best meaning , good accuracy and reliable functioning of the semi auto , it always seemed to happen not at the min. load or the max. load but in between the two. So with semi autos, I start in the middle , do a few loads +0.2 and a few -0.2 from that weight and see where the accuracy level is best and the gun still cycles 100 %.
You mentioned 9mm , so I used the semi auto as an example.
With Cast Lead bullets in 30 cal. Rifles it seems that 1600 fps is a sweet spot for accuracy, at least in my 1903A3 Springfield 30-06 and model 94 30-30 Winchester.
Gary