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.
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
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.
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.
7.25 MOA on the dial
19.25 MOA on the dial
34 MOA on the dial
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
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.