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7MM Nosler ABLR

 
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  #15  
Old 04-07-2014, 05:29 PM
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Re: 7MM Nosler ABLR

All I can say about it is I have seen it over and over especially with big 338's. The loads shoot right at or just under 1 moa at 100. Usually 3 groups of 3 shots ea.. Then I take them to 200 or 300 yards and the same loads shoot .5 moa or better repeatedly. Now not just once in a while but quite often and I work up loads for over a dozen long range rifles a year. That is a conservative figure.

Call it what you want, but if they fight me at 100 I take them farther to confirm what I really have.

Jeff
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  #16  
Old 04-09-2014, 09:41 AM
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Re: 7MM Nosler ABLR

Mind you I have not shot a ton of different bullets but the half dozen I have shot always are equal MOA measurements or better from 100 yards to 400. I know that some people have different results but I have yet to see them.
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  #17  
Old 04-09-2014, 11:42 PM
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Re: 7MM Nosler ABLR

Quote:
Originally Posted by Broz View Post
All I can say about it is I have seen it over and over especially with big 338's. The loads shoot right at or just under 1 moa at 100. Usually 3 groups of 3 shots ea.. Then I take them to 200 or 300 yards and the same loads shoot .5 moa or better repeatedly. Now not just once in a while but quite often and I work up loads for over a dozen long range rifles a year. That is a conservative figure.

Call it what you want, but if they fight me at 100 I take them farther to confirm what I really have.

Jeff
If you have a rifle/bullet combination that consistently does this then it would be great if you could set up a test and demonstrate it. Perhaps it could be done by putting up a target aimpoint at 300 or greater but not actually dialing the elevation in the scope. Then some very thin cellophane or rice paper could be set up at 100, 200, and 300 yards that would indicate the group at those ranges. It would be very interesting to prove that what many think is happening really IS happening. We will never know for sure until we actually observe this decreasing dispersion in group size of the same set of bullets.

Until that happens I'll stand on my belief that if such a test is performed, we will see that the groups never get better with range because there is no way for bullet to steer itself back into a group.

That said, I accept without question that people do see what Jeff describes above...where for some reason they are shooting better angular groups at 300 than 100. The question is why, and if we ever figure it out my bet is that it will have to do with aiming error due to parallax as was mentioned, or a human factor of some sort. I know for sure it is very common for people to shoot better groups when they can't see them for example. It's not something to dwell on because it's not a bad problem to have( unless you are a 100 yd bench rest shooter) but I would like to know the answer out of sheer curiosity.

So, if you can demonstrate this phenomenon consistently and repeatedly then someone please record it using the method I described or a better method and give us gun geeks another ballistics subject to consider when we should be working!
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  #18  
Old 04-10-2014, 06:47 AM
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Re: 7MM Nosler ABLR

Bullets that are launched out of a barrel off axis will do some wacky things before the immense rotational forces overcome thier crooked launch and cause their rotational axis to align with their direction of flight.

This scenario will cause a bullet to be flying much more stable at 300 yds than at 100 yds. Givin that rotational energy slows at a lesser rate than forward energy its not unusual for bullets to become more stable as they fly. Exactly like a top that was not started straight. Except the 200,000 rpms of a bullet tend to straigten it out much faster.

If the bullet is out of balance because of a physical flaw, it may have much more trouble flying straight, and the faster its spun the worse it gets.

This being said,
Long bullets are more difficult to get straight than short bullets, and the tighter twist required to spin them can exaggerate this entire process taking longer for the bullet to settle down. These scenario can lead to a gun that shoots 1" at 100yds and also at 300 yds. The bullet is not returning to its original flight plan its just simply stopped getting worse.

The best thing to do is to start the bullet into the barrel straight. This will drastically decrease the amount of time it takes for a bullet to align itself, resulting in tighter groups near and far.
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  #19  
Old 04-10-2014, 10:34 AM
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Re: 7MM Nosler ABLR

Whether or not this alone is responsible for the problem, i see it often testing loads, typically more often with big long bullets, and do my best to rid it by paying more attention to my reloading.
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  #20  
Old 04-10-2014, 05:56 PM
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Re: 7MM Nosler ABLR

If runout is a culprit somehow I wonder if we sometimes induce it from magazine loading. Long bullets set well out if the case hitting the ramp as the are being fed from a magazine...
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  #21  
Old 04-10-2014, 07:19 PM
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Re: 7MM Nosler ABLR

Put me down as another guy who's seen long bullets tighten up at long range vrs 100 yds.
Not sure why people would be in a tizzy about it.
A 1.5" group at 100 means bullets are landing 3/4" away from center of aim....can't think of any game animal that can't be dispatched at 100 with that?
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