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How i Test Ballistic Coefficients-Matrix 175gr

 
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  #1  
Old 06-20-2012, 04:31 PM
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Location: Tri-Cities, WA
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How i Test Ballistic Coefficients-Matrix 175gr

I have had time to do some extensive testing now with the Matrix .277 cal 175gr VLD. Here is my rifle info, how i determined bc, and the final results.

THE RIFLE

BAT Action.
27" 5-R Rifled 1-9 twist Benchmark barrel.
270 WSM .180" freebore, .310 neck.
Norma brass seperated by weight and match prepped.
Bullets seperated by Ogive. 2.265" BTO (-.020").
65.8gr H-1000. (very hot)
2,990fps Avg MV, ES 13, SD 5 (Veryfied by two chronographs)
Nightforce NXS 3.5-15x50 NPR1 .25 moa

THE PROCESS

I measured out a perfect 100yd distance target using a 300ft tape measure.
My reticle is set dead level by using a vice at the range. I use a level to set the action perfectly level on the vice.
I set up a plumb bob at 100yds.
With the rifle dead level, i level the reticle with the plumb bob down range. Once the rings are tight and i am confident the scope is level with the rifle, i install and level the anti cant device.
I shoot 3 shot groups at the measured hundred yard target, first to zero, then i dial up 20 moa and shoot another 3, then up 40 moa and shoot the last 3. I measure the distance between the groups
with the reticle and then a tape measure to make sure my rifle is tracking level and accurately.

I used the Gseven ballistic engine and the Shooter ballistic engine to verify the data because they agree with each other perfectly. I used the same target board and backed up for each extended distance.
Knowing that i have a sub 1/4 minute load, perfect 100yd zero, and a scope that tracks perfectly, i feel confident in the measured results. Ranges were measured with a Gseven BR2 Rangefinder 3 times each for
accuracy. The target was a large 4'x4' pylwood stand covered in white butcher paper.
My shooting spot is in the bottom of a canyon with a 3mph head wind. It is almost perfectly North to South so the wind is consistent in both speed and direction.
There is no East to West bearing so there is no Coriolis Effect, making it a perfect site for testing BC with drop.
Distances can be shot out to 1611 yds with almost no angle compensation.

ATMOSPHERICS

82F
29.1 HG
600F
50% RH

Here are the ranges i shot, adjustments i used on the dial, and the measured distance from the group average to the point of aim. I like to shoot as close to the edge of supersonic as i can get so that i have a good average BC. These are the inputs i used in the Gseven ballistic engine and used the "True Bullet BC" option.
I used a ProChrono that has a history of accuracy, and the Magnetospeed. They agreed within a couple of fps with each other so i did not true the velocity, only the BC.

458yds
7.25 MOA on the dial
+2" high

866yds
19.25 MOA on the dial
+8.5" high

1240yds
34 MOA on the dial
+9.18" high

THE RESULTS

My lot of Matrix bullets measure 1.49" in length with an average Meplat diameter of about .060".
Average BC with a MV of 2,990fps

G7 BC=.3225
G1 BC=.6435

I put this in the ELR thread because i feel an accurate set up and BC is essential for ELR shooting. Its a good way to test a bullet that does not have an accurate factory BC.
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  #2  
Old 06-20-2012, 06:40 PM
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Join Date: Dec 2011
Location: Greenville, NC
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Re: How i Test Ballistic Coefficients-Matrix 175gr

Great write up, I saw some of your earlier load testing over on the hide. Looks like from the manufacturers specs on that bullet they are claiming .7828 BC (static). Doesn't look like they were very close to that mark. I've been waiting on the new Bergers to decide if I'm going to rebarrel my.270wsm to a faster twist and try to run some.
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  #3  
Old 06-20-2012, 07:13 PM
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Location: Tri-Cities, WA
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Re: How i Test Ballistic Coefficients-Matrix 175gr

In truth i was a little dissapointed in the BC of the Matrix, however it is the most accurate bullet i have yet to test. I think the accuracy and consistency are worth giving up a few BC points. They are the most consistent bearing surface i have seen with an extreme variance of only .003". Most are within .001". I think that part of the BC loss if from the large Meplat diameter. I plan to try tipping them to .033" and retesting. As of right now the 7 WSM with a 180gr Hybrid beats the 270 WSM Matrix combo ballistically. My initial goals were to beat the 7. Now if i can tip the bullet and match the 7 ballistically but beat it accuracy wise i will be happy.

So far a G1 of .674 at 2,950fps is the number to beat to make the 270 WSM worth the loss of barrel life over the 7.
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  #4  
Old 07-04-2012, 10:10 PM
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Location: SW Montana
Posts: 4,377
Re: How i Test Ballistic Coefficients-Matrix 175gr

Great thread, missed it somehow! I ran out of 165's a few months ago and I've been shooting up a couple boxes of 175's, your BC seems very good and matches what I shot out to 1450 yards. My rifle shoots the 165's amazing and the .650 bc worked way out there but I have only shot them using Loadbase, the 175's I've been shooting with Applied Ballistics.
Really looking forward to the Berger, if they shoot as well as the Matrix it'll be super nice!
It'll be interesting to see what pointing will do for the BC as well, I like the Meplats the way they are for hunting though since we had very good performance on game with them.
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Old 07-04-2012, 10:40 PM
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Re: How i Test Ballistic Coefficients-Matrix 175gr

My next goal is to test the pointed matrix alongside the non pointed ones at 1,400 yds for vertical dispersion, then shoot them both again through ballistic gel at the same distance to compare expansion. It may be a couple of Weeks but I will post it in this thread.
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  #6  
Old 07-04-2012, 10:58 PM
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Re: How i Test Ballistic Coefficients-Matrix 175gr

You get double bonus points for the ballistics gel test!!!!!! I really only shoot bullets with the final purpose of killing game so the pointing kinda makes me nervous but it may weaken the point enough that it will give easier and be fine, or not.
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  #7  
Old 07-04-2012, 11:20 PM
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Re: How i Test Ballistic Coefficients-Matrix 175gr

Well it accomplishes two curiosities of mine. The success of the non pointed is well documented, so I figure if I use that as a control test for the ballistic gel, if the pointed bullets perform similarly I'll know i'm good to go for hunting with pointed bullets. Second is that there seems to be a lot of controversy over ELR hunting. The popular opinion is that a bullet needs to be traveling at 1,600-1,800 fps to be effective. I think that number may have been generated from a theory without actual testing. As far as I know no one has tested the terminal performance of these bullets at ELR. There are documented kills for sure but it will be interesting to see the gel test and the effect of pointing them.

After testing them, if they perform acceptably I plan to start a thread called "The ELR Challenge" where I am going to set up my target board beyond 1,000 yds with a target of a full sized mule deer buck and challenge myself and everyone else to make 3 cold bore hits on target. I don't want to do it to be argumentative but only to satisfy my curiosity and challenge myself.
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