Not possible...or is it?

[elmerkeithclone]

I was just reading an old gun rag article written by Craig Boddington titled "The Trouble With Long-Range Shooting". In this article Boddington makes this comment! Quote: "This Remington 7mm RSAUM actually grouped a tighter MOA at 300 yards than it did at 100 yards-serendipitous but true".

I realize that as the distance increases so does the size of the minute of that angle. If all factors remain constant then the size of the group at 100 yards has to increase proportionately to the distance....it can't get smaller!

Maybe on a given day the author shot a better group at 300 than he did at 100 but but to claim that the gun shoots tighter groups(MOA) when the distance is trippled is against my better judgement and the law of physics.....or am I missing something?

 

[Amigo Will]

Yep I remember a little fat rookie cop touting the shotgun in his first rag story and screwing up half the facts. His name was Maas something.

 

[gunbugs]

I think it was Massaads a'boob. Most, but not all gun writers make my brain hurt. Seyfreid, Boddington, etc. are difficult for me to have any interest in. But thats just me I guess.

 

[rbuck351]

If you shot through two targets with the same group, the further out would be larger even assuming the first target did no damage to the bullet or its flight. There is another factor involved. If you happened to have a scope that was parrallax adjusted fora longer range, say 200/250yds, it is very possible to shoot two groups with the further one being smaller.

 

[MontanaRifleman]

It's a fairly common occurrence. I have seen the same size groups at 100 and 200 yds. I've seen 1/2" groups at 100 and 200 yds with my Sendero 25-06 from the same load on the same day. It's due to a phenomenon called eliptical swerve which is the pitching and yawing of a bullet early in in it's flight path.

Bryan Litz posted this thread in LRH with a video to help visualize it.

http://www.youtube.com/watch?v=KH9SCbCBHaY&feature=player_embedded#at=81

http://www.youtube.com/watch?v=KH9SCbCBHaY&feature=player_embedded#at=81

Here's an article on his website... he's got a few good ballistic articles.

http://www.appliedballisticsllc.com/epswerve.html

 

[elmerkeithclone]

If you shot through two targets with the same group, the further out would be larger even assuming the first target did no damage to the bullet or its flight. There is another factor involved. If you happened to have a scope that was parrallax adjusted fora longer range, say 200/250yds, it is very possible to shoot two groups with the further one being smaller.

The picture of his rig shows it wearing a Kahles scope with no adjustable objective and this is before anybody put the parrallax adjustment opposite the windage adjustment. Most likely the parrallax is set closer to 100 than 300. He makes no mention of it in his claims. Since the article was covering the details involved in long range shooting I'm guessing that had he altered the parrallax he would have mentioned it....maybe not!

 

[Smokey]

I'm not sure my brain can wrap around this - perhaps I shouldn't even try.....

 

[BrownBear]

I don't know about 100 vs 300, because I haven't seen that. But my favorite 7 mag shoots roughly the same at 100 and 200, but only with boattails. Fred Huntington claimed it was because the boattails hadn't "settled down" at 100 or some such when I asked him about it, saying he saw the same thing with his Rockchucker using longer bullets until he upped the twist rate a bit. Long ago in a land far away. I'm open to other explanations, but it happened for me in that one instance.

 

[tyrex13]

Anything less than 10 shot groups are an absolute joke and have less than zero relevance. Most gun rags will hold up a 3 shot group and say "see, clover leaf". What a pile. 3 shot groups are great for narrowing down approximate scope zero but tell you nothing of a rifles or loads accuracy. Do the same 10 shot group 5 times and I will listen to what somebody has to say about accuracy.

 

[MontanaRifleman]

I'm not sure my brain can wrap around this - perhaps I shouldn't even try.....

Probably the best way to describe it is that sometimes bullets will "wobble" a little (pitch and yaw) when they leave the muzzle, then eventually settle down or "go to sleep". Sometimes they go to sleep in 50 yds, sometimes maybe 300. With both of my Senderos I usually get better MOA groups @ 200 and 300 yds than @ 100 yds. Not necessarily better inch size groups but almost always better MOA. The best MOA range seems to be about 200-400 yds.

 

[rbuck351]

If the bullet leaves the muzzle at 1/2 degree of angle to get to 100yds at 1MOA, the bullets are not going to magically all turn toward the point of aim as apposed to any of the other 359 degrees they could all of a sudden turn toward. It could happen from time to time with three shot groups but certainly not on a regular basis. MOA could get better at longer range as the bullet "goes to sleep" becomes stable and quits wandering randomly but group size just won't get smaller farther out. Different manufactures have used different parrallax correct ranges over the years and I have no idea of the setting of the Kahles in question. And I agree that 3 shot groups don't say much. For those that have trouble getting this picture, take a ruler and paper and make two equal length lines touching on one end and an 1" apart on the other. Now about in the middle of the lines place two points an inch apart perpendicular to the centerline of the angle. Now put the ruler on the closed end of the angle and one of the mid point dots. This will show where the bullet is headed unless they all magically turn toward the center of the angle. Yes it is possible to shoot as small or even smaller groups at longer range but it's not sleepy bullets all turning toward the same point in space from the half way point on. As parrallax usually becomes less of a problem as you get further out, I suspect that has much to do with this.

 

[jim in anchorage]

[QUOTE"This Remington 7mm RSAUM actually grouped a tighter MOA at 300 yards than it did at 100 yards-serendipitous but true".
][/QUOTE]
So? The 100 yard group could have been 1", the 300 2 7/8". That fits the statement and is hardly shocking.

 

[MontanaRifleman]

If the bullet leaves the muzzle at 1/2 degree of angle to get to 100yds at 1MOA, the bullets are not going to magically all turn toward the point of aim as apposed to any of the other 359 degrees they could all of a sudden turn toward.

With eliptical swerve, the bullet is not leaving the muzzle at 1/2 degree off. It's "wobbling" along a fairly consistant flight path until it settles down. It's really nothing new and is observed and understood by most competitive shooters.

 

[Smitty of the North]

With eliptical swerve, the bullet is not leaving the muzzle at 1/2 degree off. It's "wobbling" along a fairly consistant flight path until it settles down. It's really nothing new and is observed and understood by most competitive shooters.

I think that's correct.

It's been observed, and there are plausible explanations for it.

As far as I'm concerned, "End of Story".

Smitty of the North

 

[rbuck351]

Well, let me put it another way. If the bullet is deviating away from the group center, and it had to to get anywhere other than dead center, it is not going to change from its present flight path away from center back toward the center of the group unless acted upon by some force. The odds of all bullets shot to the left of group center turning back to the right and all bullets shot to the right turning back to the left is highly unlikely. The Idea of a rifle shooting 1" at 100 and 2 7/8" at 300 is easily within normal sizes for any two groups especially if large numbers of rounds are not fired.

 

[MontanaRifleman]

Well, let me put it another way. If the bullet is deviating away from the group center, and it had to to get anywhere other than dead center, it is not going to change from its present flight path away from center back toward the center of the group unless acted upon by some force. The odds of all bullets shot to the left of group center turning back to the right and all bullets shot to the right turning back to the left is highly unlikely. The Idea of a rifle shooting 1" at 100 and 2 7/8" at 300 is easily within normal sizes for any two groups especially if large numbers of rounds are not fired.

There are physical forces acting on the bullet that are affected by it's weight, shape, velocity and rate of spin. I don't know all these forces but I have to some degree seen their affect. When I was a kid I used to play with tops... give'em a good flick off the string and watch them spin. They stood upright on the tip of their point because they were spinning and they moved and wobbled a little and when they slowed way down they fell over. While they were spinning, you could push them with your finger and they would remain upright. I didn't fully understand it, but it happened. How about baseball? Curve ball and Knuckleball? They change direction in mid flight. There are also some other forces that act on bullets that are not noticed until way down range... such as Coriolis and spin drift. Spin drift is kinda like a curve ball.

In my experiences, I have seen as much as 1/2 MOA @100 tighten up to 1/4 MOA @ 200 and almost always, at least a slight improvement in MOA @ 200 vs 100 which is usually carried out to 300 and 400 yds. When I'm evaluating the accuracy of a load, I never do it @ 100 yds other than to see if it's less than MOA and work up velocities and pressures. 200 yds is where I start to evaluate real accuracy.

 

[rbuck351]

I know this actually happens and I'm not arguing that at all. What I am saying is I have a problem with the cone of despersion (sp) getting bigger as would be expected and then reversing. If that were the case , then somewhere along the line group size should go down to zero. I haven't seen that happen yet. I don't think it's possible to make a scope with perfect 0 parrallax at two different ranges and I believe this could easily account for minor odd group sizes at different ranges. And because of a bunch of factors ( twist rate, velocity at given distance, eliptical effect and a bunch of other stuff), there's no real way of knowing what a 1/2" group at 200yds actually was at 100 but I'm guessing smaller. We can immediatly fire another group, but it will not be exactly like the last one. Too many variables including the human factor. I have fired a parrallax adjustable scope delibertly set at the wrong range to see what effect it has. If set for 300 and shot at both 300 and 100, the 300yd groups will probably be much smaller.

 

[elmerkeithclone]

I know this actually happens and I'm not arguing that at all. What I am saying is I have a problem with the cone of despersion (sp) getting bigger as would be expected and then reversing. If that were the case , then somewhere along the line group size should go down to zero. I haven't seen that happen yet. I don't think it's possible to make a scope with perfect 0 parrallax at two different ranges and I believe this could easily account for minor odd group sizes at different ranges. And because of a bunch of factors ( twist rate, velocity at given distance, eliptical effect and a bunch of other stuff), there's no real way of knowing what a 1/2" group at 200yds actually was at 100 but I'm guessing smaller. We can immediatly fire another group, but it will not be exactly like the last one. Too many variables including the human factor. I have fired a parrallax adjustable scope delibertly set at the wrong range to see what effect it has. If set for 300 and shot at both 300 and 100, the 300yd groups will probably be much smaller.

rbuck351, My thoughts exactly!

MR I understand what your saying to a degree! I just can't get a hold of the fact that if the bullet is off course at 100 by an inch do to bullet wobble then even if the bullet settles down and flies true from that point on. Since it is indeed one inch off course and the angle of flight has already been determined then even a bullet flying perfectly isn't going to by chance wander in the right direction decreasing the angle. It would be just as likely to wander even further off course. I'm not saying this as an absolute but more thinking out loud and second guessing myself at the same time.

I so rarely shoot groups at more than 100 yards that this is unfamiliar water to me! Mr if you say your Sendero's shoot better at 200-300 than 100...well I believe you! I'm going to shoot some of my rifles at greater distances now just to satisfy my own thinking.....I think!

 

[MontanaRifleman]

EKC, I understand what you and rbuck are saying. I am by no means an expert on the subject and all I can do is relay my experiences. When I accurize a load, I do it at 200 yds or more and not 100. The only time I shoot 100 yds is for initial pressure load testing and to maybe get a wag on the accuracy. At the range where i shoot, they have target boards set up @ 100, 212, 330, and 427 yds and then a semi-private 100 yd lane. I often use the 100 yd lane because the other range often has quite a few shooters using it and it's a pain to get my chrony set up and read it when I'm firing. If I had a 200 yd range to work on, that's where I would do most of my load development and then confirm accuracy at farther ranges. For instances, I've just been working with combination's of 3 different bullets and 3 different powders - 5 total combination's in my 300 RUM and I did all of it (initial load work, not accuracy) on the 100 yd lane because it was the easiest thing to do. Now I have three 5 shot loads ready to go of RL17 and GS 177's which show the most promise for what I am looking for. I will do these on the 212 target boards for accuracy, and if one is significantly better than the others, I'll go with that. If I don't get the accuracy I want, back to the drawing board. If I do, then out to 330 and 427. So using this method, I bypass 100 accuracy, so maybe that's why I have experiences with better angular (MOA) accuracy at farther ranges.

In the other forum I hang out in, there are a lot of BR and F-class members and they all do pretty much the same thing... some even skip 200 yd accurizing and go right to 300 or 400, then ladder testing from 600 - 1000. If you did a poll over there, the great majority of those guys would say that 100 yd accuracy testing is meaningless and these are guys with a whole lot of precision long range shooting experience. If you can hit a tennis ball @ 600 yds then you can hit a tennis ball at 100 yds.

Now if your thin is 100 yd shooting, competitive or whatever, then do your accurizing at 100 yds. If you want ragged holes @ 300 yds, accurize @ 300 yds.

So if you want to test this theory out, just by-pass the 100 yd shooting and work up an accurate load @ 200 or 300 yds. Then go back and shoot @ 100 and see what you get. The reason I'm saying this is, if you accurize at 100 yds, then you might find a load that goes to sleep early or doesn't "wobble" much or at all. Also, you'll probably see this phenomena more with longer, low drag bullets. Bergers, SMK's, etc., and possibly thinner vs heavier barrels. I would be interested in hearing your results.

And BTW, the example of my 25-06 shooting 1/2 MOA @ 100 and 1/4 MOA @ 200 (212) is porbably my most extreme experience. And once I have a load worked up, I almost never shoot it less than 200 yds.

 

[allen-ak]

303 Brit and Enfield rifles were well noted for this very thing.
They round, gun would not "settle in" to 800 yds. Shot better MOA farther out, not in close.