Do Groups Grow Bigger with Distance?

[alinwa]

So, let's look at this backwards. Would Mr. Overmans recent 1.077" 1000 yard group have measured larger or smaller than 0.108" at 100 yards.

Irrelevant, not in any way related to the subject at hand.

 

[Boyd Allen]

Donovan,
Shame on you! Hard data, with pictures, in one of these "theoretical" discussions? How rude. What were you thinking? ;-) Seriously,nice work; thanks for sharing.
Boyd

 

[Guy Pike]

To answer the original question I must state then undisputed, immutable fact: Mine do!

 

[goodgrouper]

Donovan,
I appreciate your contribution here and thank you for showing it. But I wonder just exactly what the experiment shows, other than how much 145 feet of velocity spread can effect the vertical in one's group. Maybe that's what you were aiming for (pun intended), but I think it's a seperate issue. In your case, there is no possible way to test our phenomenon on it's own because you've added in so much inherent spread in velocity. What you'd need to do is pick the best load (smallest SD and ES combined with best 100 yard accuracy), load up 5 rounds of it, and then fire them through your medium. Then run your percentages.

However, since you're shooting Dtac's, it's no doubt you're using a custom barrel, and an already pretty accurate cartridge with outstanding close range accuracy. So you'll probably not see anything unusual and such a test may be a waste of your time. As I said earlier, every time I've seen a gun ignore MOA, it has been in very rough, firecracked barrels using long-for-caliber bullets that didn't produce the best 100 yard accuracy but had loads that produced low SD's. If you ever happen upon one of these guns, it will leave you scratching your head, but in a good way!

 

[goodgrouper]

goodgrouper -

The primary gun I've done it with is a 1000-BR rifle with 6Dasher barrels and from 105/107/115 type bullets, but on 2 occasions I did use a 6PPC (Lt-V) with 66gr & 70gr match bullets.
As I wrote, when group testing, a 22 to 28% dispersion increase from my best hitting loads (18 to 22% best case scenario) over the 400yds from 100 to 500yds.
You can doubt all you want, makes no difference to me, I conduct those tests for my own knowledge and are not some highly documented report. The barrels, gun, bullets, loads were very capable of high precision, with most groups being under 2" at 500yds and several much smaller.
I shared that ladder test because it shows vertical dispersion well (but does show the horizontal), but group testing is by far what I did the most of. From those 25 to 30 sessions over a couple years time, I would estimate I shot somewhere around 200 to 250 5-shot groups to the multi-target scenario.

Donovan

Donovan,
I guess you misunderstood me. I wasn't doubting you at all, and I of all people appreciate personal experiment results over internet theory. My point was that what you tested was not precisely relevant to the phenomenon this thread is about. They are two seperate issues.

 

[goodgrouper]

Goodgrouper -

On a separate note here, why would quote the images back, and clutter the thread?
Everyone can see/view my posts as is.
If your referring to a single statement and quoting it ...cool.
But the 100% re-posting quotes, and in this case, pictures, is simple just clutter --- IMO

Wow....seriously!? You act like I just slapped your mother by making a suggestion and then you complain about something as insignificant as this? Well, thanks for the humor.

Secondly, instead of telling me how you think I should conduct a test, why don't you do it yourself.

I did. Check post #23.

 

[dmoran65]

Simple answer: yes they do usually get bigger. But they can be smaller too, in MOA. Not in actual inch measurement. Seen it with my own eyes dozens and dozens of times with multiple guns, multiple calibers, multiple conditions. But each time, the bullet used was VLD in shape or heavy-for-caliber tangent bullets. The Aberdeen tests I read about were all done with standard ball ammo from standard twist rates decades ago.
Here's the current data Bryan Litz has shown: http://www.youtube.com/watch?v=4pF8W...e=channel_page

Forgot to mention, for those that don't know, Bryan Litz is an Aerospace engineer who used to work for the armed forces and is currently chief ballistician for Berger Bullets.

Not seemed.Were.
I'll give you the latest example I have. Three weeks ago, I was working on an old, burned out 300 win mag that was way past it's prime. Severe fire-cracking 5" down from the throat. You know the type, the kind that takes days to get completely clean. Well, this gun wouldn't shoot ANYTHING under 1.5" at 100 yards no matter what powder or charge weight I used. But the bullet that seemed to work best was a 200 grain Accubond. After 6 days at the range, I found a load that shot about 1.5" to 1.75" pretty consistently and had good deviations. I loaded up five more rounds right there on the spot and fired them 5 minutes later at 550 yards. The group went a bit under 4", but four of the five shots were smaller than that with two even touching.
Now I've heard all the theories and excuses (mirage, wind blew it in, parallax, etc etc etc) why this happened, but this has happened so many times I'm actually shocked that more "experts" here haven't seen it too. But, I guess, unless you're shooting long distances with different guns 3 or 4 days a week like I do, maybe you won't see it. But I swear on a stack of Bibles that it happens. And I'd be a fool to witness this as many times as I have and then disregard my own experiences in favor of some "accepted facts" on the internet.
So take it for what you will and do with it as you please. All I'm saying is don't throw away that old gun just because it won't shoot as good as you'd like at 100 yards.

So you're saying you've run cables to your acoustic screens out to almost a quarter mile? WOW. That's gotta be a 'ell of a spool of wire.
Would you mind telling us what screens you used, who is "we", and why you didn't document any of this if you went to that much work?

So far, this has been mostly about longer range phenomenon and it sounds like there has only been a handful that have ever tested it. But what about shorter range tests? In short range BR, I've heard many a folk say that one bullet or another shoots better at 200 than 100. Seen that one myself as well..........the Berger 65 BT shoots dots for me at 200 but is only mediocre at 100. And that's been in a half dozen barrels or more. I suspect there are multitudes of folks who have seen this but are not going to say a word here.

One thing I do find interesting though is the fact that the ones who want more tests to be run to convince them of this also seem to be the ones who's minds are already the most made up about what results they will see! That is a terrible scientific approach! Researchers MUST enter into a test with an open mind...............

Ohhhh boy. I'm not sure what to make of any of this and I wonder why that is par for the course when I ask Al something! First you say you did acoustics, then you say you are planning to do acoustics, then you say it's gone, then you say you did paper instead? But apparently you did at least run one gun that was "supposed" to show this before everything was taken away.........? Oh yeah, you've got stacks and stacks of documentation from it. OK. Fine. It's not exactly the most believable testimony, but I guess it'll have to do. What else should I expect from the man who owns every t-shirt and has had drinks with everyone in the book of Who's Who? Well, we won't go there......

Now, if you don't mind, I'd like to make a few points here in defense of my observations since you seem to believe that I've not spent any time, money, or effort trying to learn what's going on here.

First, I'm very aware and familiar with an Oehler 43. Used one a time or two. Even helped set up an indoor range built around using one. I never ran one out past 100 yards (indoor tunnel), but I recall a man setting one up to shoot through at 1000 yards in the Varmint Hunter magazine I believe it was. I remember him saying that rodents started gnawing on the cables and he finally ended up having to run some protection over the wires. In this man's tests, he reported BC's INCREASED as the yaw of nutation dampened. Because of the accuracy of the test instrument, he could see exactly where this occured. For some bullets, it was farther out than others. Perhaps this is what Sierra has found too as they list velocity boundaries with their BC's and have printed in writing that BC's were very often higher at longer ranges. Now, this day in age, one can find info on either side of a debate and state that it is "truth". You say you've found info to mirror your results and I have no doubt that you have. I've got info that is opposite, and that's all fine and dandy. But I really don't care about what is "supposed to happen" as much as what "actually happened". As I said, I've seen it many times with my own eyes. I guess the next gun I work on that shows this weird phenomenon, I'll have to get out the video camera! But would that really change anyone's mind if it's already made up? Doubtful. But what I would like someone to explain is why can't a gun shoot a group that measures 1.75" at 100 and 4" or 5" at 550? Or worded a different way, why did the bullet not follow MOA? Not absolutely sure, but each time I have seen this happen, it has been with long bullets in very rough factory barrels, with loads that had very low standard deviations.

Secondly, convergence, as you call it, is not what I'm talking about. What I'm talking about are bullets that are more susceptible to wind drift and other atmospherics while they are yawing, and then less susceptible after the yaw has dampened. I feel this is important to understand since the majority of us shoot bullets on Earth, in an atmosphere, through air currents. Now, where those currents exist in relation to the bullet's own flight path, and what condition the bullet is in make all the difference. Would the gun I referenced a few weeks ago show what it did in a vacuum? I suppose not. But I don't much care since I've never shot in a vacuum, nor will I probably ever get to. But through 550 yards of atmosphere, this gun shot smaller MOA than it did at 100. Routinely. On a smaller scale, it has been reported by many BR shooters that one bullet works better at 200 than 100. So, there is proof (or contradictory information, whatever you want to call it). At least, to us that have seen it. Since I'm not a drinker, I can't blame the booze for what I saw! Now, I could quote Rinker, Sierra, Litz, McCoy, etc., etc., that bullets have higher bc's when they quit yawing, but then you'd quote your sources that contradict that and we'll wind up right back where we started, in personal experiences. You saw X, and I saw Y. It sure wouldn't be the first time that has happened!
Maybe the reason we saw different things is because the topic itself is very hard to duplicate, non-frequent, and vary variable. Also, it's very expensive to test it. You'd need four or five accoustic targets with downrange amplifiers, a discountinued and rare OM43, or a OM83 or OM85, a ton of wire, and a 1000 yard range that wouldn't mind you shutting everything down while you ran your tests. So until then, I guess all we can go off of is our own personal observations. And I have to remind myself that very few folks are in the unique position I am to witness this type of thing.........

Donovan,
I appreciate your contribution here and thank you for showing it. But I wonder just exactly what the experiment shows, other than how much 145 feet of velocity spread can effect the vertical in one's group. Maybe that's what you were aiming for (pun intended), but I think it's a seperate issue. In your case, there is no possible way to test our phenomenon on it's own because you've added in so much inherent spread in velocity. What you'd need to do is pick the best load (smallest SD and ES combined with best 100 yard accuracy), load up 5 rounds of it, and then fire them through your medium. Then run your percentages.

However, since you're shooting Dtac's, it's no doubt you're using a custom barrel, and an already pretty accurate cartridge with outstanding close range accuracy. So you'll probably not see anything unusual and such a test may be a waste of your time. As I said earlier, every time I've seen a gun ignore MOA, it has been in very rough, firecracked barrels using long-for-caliber bullets that didn't produce the best 100 yard accuracy but had loads that produced low SD's. If you ever happen upon one of these guns, it will leave you scratching your head, but in a good way!

Wow....seriously!? You act like I just slapped your mother by making a suggestion and then you complain about something as insignificant as this? Well, thanks for the humor.

I did. Check post #23

Great tests!!! Obvious results!!!
I will pull mine, since yours are so much better and totally on topic..... and leave the thread all to you

 

[goodgrouper]

Great tests!!! Obvious results!!!
I will pull mine, since yours are so much better and totally on topic..... and leave the thread all to you

Never ceases to amaze me how emotional some folks get when you present a differing view, or make a suggestion........... Sheesh.

 

[JerrySharrett]

Tee hee Donovan, don't tell anyone you are an accomplished 600 yard shooter and Caterpillar mechanic.

 

[chino69]

Wilbur,
You are 100% correct about the accident at TMI. If the operators allowed the safety shutdown systems to inititate, as they were designed, there would not have been an accident.

 

[Joe Maisto]

Have any of Y'all witnessed a case where it SEEMED that groups were smaller (or relatively smaller) at a longer distance - from the same rifle.

often happens to me. I'd just as soon do away with the 100 and just shoot the 2. I think maybe I try harder knowing the outcome if you don't.