Gun groups better @ 200 than 100yrds

[Icantshoot]

308 rem 700 20in tube 1-12.
47 re15 150 nos bt cci mag primers win cases 2.8
Groups one inch or a little under 100 yrds @ 200yrds .400 3 shot & .535 3 shot last shot i was getting a little excited.
My question is why does it group better @ 200 than 100 also I dont have a chrony anyone have an rough idea velocity with this load and 20 inch tube.
Thanks for any input.
JRG

 

[rscott5028]

You need a much larger sample size to be statistically valid.

...but, nice shooting nonetheless

 

[Browninglover1]

You need a much larger sample size to be statistically valid.

...but, nice shooting nonetheless

Agreed 100 percent. In theory I think it would be impossible without a guidance system to make groups smaller (in terms of inches) as distance increases. I've seen guns that shot better as the distance got longer in terms of MOA but the actual group size in inches never got smaller.

 

[venom600]

I've seen guns that shot better as the distance got longer in terms of MOA but the actual group size in inches never got smaller.

My 300 RUM is that way with several of my loads. Never smaller in inches, but noticeably smaller in MOA/MRAD at longer distances.

--Ben

 

[Broz]

Bullet pitch and Yaw.


[ame=http://www.youtube.com/watch?v=4pF8W5liSRc]Pitching and Yawing of a bullet - YouTube[/ame]

 

[rscott5028]

My 300 RUM is that way with several of my loads. Never smaller in inches, but noticeably smaller in MOA/MRAD at longer distances.

--Ben

Others have experienced the same effect as you.

The general concensus in previous debates has been that when this occurs, it's most likely due to parallax adjustment in the scope.

Otherwise, physics doesn't really allow this to happen.

-- richard

 

[rscott5028]

Bullet pitch and Yaw.


Pitching and Yawing of a bullet - YouTube

Broz,

I beleive if you read that article that started that Youtube video circulating, the auther admits that it was created using an extreme computer model. And, that he ultimately couldn't come up with a realistic scenario where it would have any affect.

-- richard

 

[venom600]

Jeff,
Thanks for posting that, very interesting. Does that simulation assume that the bullet is missing a specific amount of concentricity, or is that valid for a concentric load?

I'm just wondering if I may be causing this phenomenon in my reloading process.

--Ben

Nevermind, my question was answered in post #11 below.

 

[Icantshoot]

Thanks i will load some more and post results.

 

[bigngreen]

Happens to me all the time cause I suck at shooting groups when I can see the bullet holes!

 

[rscott5028]

Broz,

I beleive if you read that article that started that Youtube video circulating, the auther admits that it was created using an extreme computer model. And, that he ultimately couldn't come up with a realistic scenario where it would have any affect.

-- richard

I had forgotten that Bryan Litz wrote the article. He is certainly an authority.

Nonetheless, here are a few more excerpts from the article...

Homepage of Bryan Litz - A Bravenet.com Hosted Site

In other words, if the initial pitching and yawing is aggravated randomly by muzzle blast, if you get a 1.5" group at 100 yards that increases to 3.0" at 200, etc, only 0.03" of that dispersion is due to epicyclic swerve. I thought there must be some set of initial conditions that maximizes the epicyclic swerve to be greater than 1 caliber, while preventing the aerodynamic jump dispersion from growing wildly. I tried using a large constant value of pitch rate, and varying slightly from the elevated average for several groups. I tried many different things like this, simulated hundreds of 5, 10, and 20 shot groups. Nothing produced smaller angular groups at longer range.

 

[venom600]

I had forgotten that Bryan Litz wrote the article. He is certainly an authority.

Nonetheless, here are a few more excerpts from the article...

Homepage of Bryan Litz - A Bravenet.com Hosted Site

Good article, thanks for posting that. I guess that answered the question I posed to Broz above.

--Ben

 

[rscott5028]

Jeff is probably more experienced than I am. But, I just happened to recall seeing the whole article some time ago. The illustration alone can be misleading.

 

[Broz]

Jeff is probably more experienced than I am. But, I just happened to recall seeing the whole article some time ago. The illustration alone can be misleading.

I don't know about that... But I do know I have seen more than a few loads be 1 moa at 100 and 1/2 moa at 300. And this was proven by several groups shot. This video is the only way I can explain this. So it works for me..

Jeff