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Help interpret first chrony data

 
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  #1  
Old 05-28-2008, 02:58 PM
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Join Date: Nov 2007
Posts: 45
Help interpret first chrony data

Hey all,

So I bought a chronograph and ran my latest reloads through it. Can you help me interpret the data?

I fired three loads of Varget at 44.4g, 44.5g, and 44.6g (each with federal brass, cci primers & 175g Sierra MatchKing in .308). I'm reloading with off the shelf Lyman and RCBS equipment and lee dies. I didn't seperate brass or bullets by volume or weight.

Its being shot out of a Rem700P, off a bench with rests at both ends on a virtually windless day.

I haven't played with getting closer to the lands because I want it to magazine feed so I've kept it at the book length.

I posted the velocities, group sizes, standard deviation etc.

I'm wanting to use this as my long range target round.

I'm thinking 44.6 grains is in a good spot.

Do you figure the velocities and deviations acceptable? If not, where should I start looking to improve?

Any help appreciated.

Thanks,

ST


***44.4 GRAINS***
GROUP1 shot at 100 yards
Shot 1 2702 fps
Shot 2 2718 fps
Shot 3 2728 fps
Shot 4 2726 fps
Shot 5 2764 fps
Avg Vel Grp1 2727.6 fps
5 Shot Group Size 1.2 inches
5 Shot Group MOA 1.256 MOA
GROUP2 shot at 100 yards
Shot 6 2710 fps
Shot 7 2784 fps
Shot 8 2812 fps
Shot 9 2799 fps
Shot 10 2821 fps
Avg Vel Grp2 2785.2 fps
5 Shot Group Size 0.547 inches
5 Shot Group MOA 0.573 MOA

Avg Vel Total 2756.4 fps
Velocity Spread 119 fps
10 Sht AVG Grp Sz 0.8735 inches
10 Shot AVG MOA 0.915 MOA
Bias Standard Dev 42.68 fps
***44.5 GRAINs***

GROUP1 shot at 100 yards
Shot 1 2821 fps
Shot 2 2821 fps
Shot 3 2821 fps
Shot 4 2801 fps
Shot 5 2775 fps
Avg Vel Grp1 2807.8 fps
5 Shot Group Size 0.56 inches
5 Shot Group MOA 0.586 MOA
GROUP2 shot at 100 yards
Shot 6 2754 fps
Shot 7 2702 fps
Shot 8 2669 fps
Shot 9 2655 fps
Shot 10 2629 fps
Avg Vel Grp2 2681.8 fps
5 Shot Group Size 0.992 inches
5 Shot Group MOA 1.039 MOA

Avg Vel Total 2744.8 fps
Velocity Spread 192 fps
10 Sht AVG Grp Sz 0.776 inches
10 Shot AVG MOA 0.812 MOA
Bias Standard Dev 71.15 fps
****44.6 GRAINS****
GROUP1 shot at 100 yards
Shot 1 2603 fps
Shot 2 2652 fps
Shot 3 2680 fps
Shot 4 2741 fps
Shot 5 2731 fps
Avg Vel Grp1 2681.4 fps
5 Shot Group Size 0.553 inches
5 Shot Group MOA 0.579 MOA
GROUP2 shot at 100 yards
Shot 6 2773 fps
Shot 7 2746 fps
Shot 8 2709 fps
Shot 9 2723 fps
Shot 10 2743 fps
Avg Vel Grp2 2738.8 fps
5 Shot Group Size 0.762
5 Shot Group MOA 0.798

Avg Vel Total 2710.1 fps
Velocity Spread 170 fps
10 Sht AVG Grp Sz 0.6575 inches
10 Shot AVG MOA 0.688 MOA
Bias Standard Dev 48.62 fps
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  #2  
Old 05-28-2008, 08:29 PM
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Join Date: Mar 2008
Location: Chatham, VA
Posts: 436
The velocity spread seems high to me, can you tell more about how the brass was prepped? The groups seem good considering the high spread though.

I have better luck with the 168gr bullets in my Savage .308. But others like the 175s so thats something else to try.
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  #3  
Old 05-28-2008, 09:05 PM
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Join Date: Dec 2007
Posts: 322
I like to see SD #'s in the single digits,I would try loads starting from the lowest to highest in .5 gr incraments.Once you find the best load,then you can start playing around with loads in .1 or .2gr incraments to find the "sweet spot".Be safe,and have fun.
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  #4  
Old 05-28-2008, 09:29 PM
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Join Date: Nov 2007
Posts: 45
KQguy - I did do the .3 increment workup initially to get into this ballpark as I got the best hits at 44.4 and 44.7.

Forester - The brass is once fired federal that was factory loaded. I tumble cleaned, cleaned primer pocket, uniformed and deburred flashhole, trimmed to manual suggestion, deburred in and out, full length resize, measure neck run out and case neck thickness.

I'm wondering if sorting by volume would help prevent such variation?
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  #5  
Old 05-29-2008, 05:56 AM
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I would try a slower burning powder,and see how that works.
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  #6  
Old 05-29-2008, 09:50 AM
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Posts: 45
Quote:
Originally Posted by KQguy View Post
I would try a slower burning powder,and see how that works.
What would you suggest? It's going through a 26" barrel with 1/12 twist.

I thought for sure Varget would work though as it seems very popular.

But am open to suggestions.
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  #7  
Old 05-29-2008, 04:32 PM
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Join Date: Mar 2008
Location: Chatham, VA
Posts: 436
Quote:
Originally Posted by GSoD View Post
KQguy - I did do the .3 increment workup initially to get into this ballpark as I got the best hits at 44.4 and 44.7.

Forester - The brass is once fired federal that was factory loaded. I tumble cleaned, cleaned primer pocket, uniformed and deburred flashhole, trimmed to manual suggestion, deburred in and out, full length resize, measure neck run out and case neck thickness.

I'm wondering if sorting by volume would help prevent such variation?
Sounds good on the brass prep...did you sort by runout or neck thickness or just check that it is not excessive? You said cleaned primer pockets...did you uniform them as well as the flash hole?

I know some like to FL size every time, but I have better luck neck sizing with a Lee Collet die. My brass does not get tight to chamber until about 4 or 5 firings...then I bump the shoulder and start again.

How was your runout after seating the bullets?

Edited to add: I have had good results from .308 Federal brass, but it seems soft and does not last as long. Lapua is way more consistent...and expensive. RE-15 is a slower powder, and gives me very good results.
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Last edited by Forester; 05-29-2008 at 04:36 PM.
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