30BR Extreme Spread

M

Mitch Newman

Guest
I have been chronographing my 30BR and have been averaging 3050 velocity and about 40fps extreme spread. That seems to be a lot to me. I am using 118 gr danzac coated bullets, 34,8 grains of 4198. I have a 24 inch, 17 twist Lilja barrel. Is that extreme spread normal for coated bullets?? Thanks, Mitch
 
Most point-blank benchrest shooters don't chronograph for Extreme spread. And most chronographs aren't accurate enough, or set up accurately enough, or used with a large enough sample size to get real numbers.

I believe Henry Childs recommended a 16-foot screen spacing. And as I remember, it took 50-70 shots to get meaningful standard deviation results.

Having said all that, the real question is "How does it shoot?" If you are getting vertical, that may be the cause. If you can get it down, you might have an easier time tuning your load & staying in tune.

But I will say this, even though I shoot primarily long range, I don't worry overmuch about SD/ES. I do note it, and if the most accurate powder/bullet combination has high SD, I'll note it, but go after it ONLY IF I can't get the vertical out tuning the gun, checking at 1,000 yards.

FWIW
 
It seems a bit high. But what happens on paper is what matters most. If it is a problem... check your neck tension.

Paul
 
I am dropping my charges using a Harrell Precision. Should I try weighing some to see if there is an improvement. It would probably tell me if it is my throwing rhythm that is off.
 
Take one case and fire it over the chronie 5 times and see what numbers you get.

You have to load the range to do this.

It was a simple test offered to me years ago. With carefully weighed charges in one case shot as fast as I could reload, the velocity data was no better then when I shot a normal string with multiple cases.

As Charles E said, my chrony error is more then the numbers I am trying to crunch. I use my chrony to ensure I am not about to join my ancestors but let the paper decide what I do with my loads.

Some of the smallest groups I have ever shot at 200yds had chronie numbers that looked the pits. I used to shoot over a chronie.....

Jerry
 
Thanks Guys. It does shoot really good on paper. My groups are good and tight. I am just used to trying to achieve low spread numbers. Thanks Again!!
 
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