Bullet Stabilizes at range but not close...why?

djfergus

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So here is the question: Why could I have a bullet shoot sub quarter MOA at 100yds then grow to 1 MOA at 200yds and then shrink back down to .5MOA at 300yds and 500yds. Rifle is a quality custom build in 300 WM and using Accubond bullets. SD and ES are single digit and I think I’m happy with the performance but never seen this personally. All the groups were 10 shots each so I feel pretty confident this is not a fluke.

Bullet weight is 200gr, velocity is 2900fps, twist is 1/9.4.

Thanks
I think there is a couple of different things that can cause this. I'm sure there will be plenty of responses to cover all of the bases.
 

CaptnC

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I have not seen this written so it's just my little brain buzzing through thoughts.

Think about this:

Mentally drawing a line of the bullet path.

All bullets are exiting from the same point...muzzle...ok

At 100 yards the are all one inch apart.

At 200 yards they are all .5 inches apart.

Logic should suggest as they pass 200 yards...they will continue on the same path that they left the muzzle...right?

So at 300 yards all bullet paths should be opened back up and their paths should continue to open up past 300 yards.

There is just know way for the bullets to "know" to migrate back into a group once they have separated.

At least that's how my mind works...
 

jmcmath

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Can we get target pictures?

I’m pretty impressed you’re shooting 1/4 moa 10 shot groups with a win mag and 1/2 moa 10 shots at 500, nice job.
 

djfergus

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My 400 yrd groups have been worse than my 500 yd groups. I attributed it to the 400 yard target being at a higher elevation. My bipod feet never seemed to bite in like I wanted with the rifle at the angle I was shooting for the 400 yd target
 

JASmith

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Set up a target at 200 and 300, shoot through the first target into the second, you will then be comparing the same 10 shots at 2 distances.
'Ole Doc Heisenberg will bite ya in the fanny!

There will be some effect. The question is "How Much?"

Nonetheless, the experiment will be worthwhile -- some of us would bet that the 300 yard target wont look nice.

We could make bets for kudos and bragging rights - - - -
 

djfergus

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Dec 25, 2015
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1,714
So here is the question: Why could I have a bullet shoot sub quarter MOA at 100yds then grow to 1 MOA at 200yds and then shrink back down to .5MOA at 300yds and 500yds. Rifle is a quality custom build in 300 WM and using Accubond bullets. SD and ES are single digit and I think I’m happy with the performance but never seen this personally. All the groups were 10 shots each so I feel pretty confident this is not a fluke.

Bullet weight is 200gr, velocity is 2900fps, twist is 1/9.4.

Thanks
Is your 200 yard target at the same shooting angle that you shooting the 100 & 300 from or is there another angle or another position that you have to shoot your 200 yard target from? What is your rest?
 

djfergus

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Joined
Dec 25, 2015
Messages
1,714
So here is the question: Why could I have a bullet shoot sub quarter MOA at 100yds then grow to 1 MOA at 200yds and then shrink back down to .5MOA at 300yds and 500yds. Rifle is a quality custom build in 300 WM and using Accubond bullets. SD and ES are single digit and I think I’m happy with the performance but never seen this personally. All the groups were 10 shots each so I feel pretty confident this is not a fluke.

Bullet weight is 200gr, velocity is 2900fps, twist is 1/9.4.

Thanks
Also, have you physically checked for paralax @ 200 yds?
 

djfergus

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Dec 25, 2015
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This same question & scenario comes up at least a couple of times a year on this forum. I'm pretty much convinced that it's a matter of shooting position being different, paralax or a difference in conditions/environment. It would be nice to nail down this phenomenon to a short list of things to watch for as a cause of this.
 

Pro2A

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May 23, 2009
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197
I have not seen this written so it's just my little brain buzzing through thoughts.

Think about this:

Mentally drawing a line of the bullet path.

All bullets are exiting from the same point...muzzle...ok

At 100 yards the are all one inch apart.

At 200 yards they are all .5 inches apart.

Logic should suggest as they pass 200 yards...they will continue on the same path that they left the muzzle...right?

So at 300 yards all bullet paths should be opened back up and their paths should continue to open up past 300 yards.

There is just know way for the bullets to "know" to migrate back into a group once they have separated.

At least that's how my mind works...
Ya might oughta hang an "OUT OF ORDER.......YMMV" sign on that mind.... :) :) :)
 

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