Magneto-Speed Accuracy

Yes, it is only 63fps but at 700m it was almost 2MOA or 14" difference. 700m ended up being the approximate true range given speed of sound plus air temp to get transonic flight after chrono velocity and TBH atmosphere. The way these solvers work is you take predicted drop and actual drop and true the algorithm to match drag curves. All of the really good solvers use the Point Mass root and it works really well especially with Doppler RADAR tested BC's. Deterministic variable are accurately calculated with this method; the furthest I have used this is around 2700m with a .50 BMG.

The reason I'm asking is I have not done a tall target test on this optic so it could be the optic not having accurate adjustments. I can't say for sure so I'm asking how accurate your Magneto-Speed is since I need to be able to provide meaningful feedback about this rifle platform.

Keith.. I wish I knew as much about all that bullet drop and stuff as you do but where I'm from and limited to a realistic hunting shot of 400 yards or so I have never really needed to be as persist as you will need to be shooting as far as you do.

Now here's a question for you.. How would I test my new magneto speed for accuracy.. I would need to know the exact velocity of a bullet before it is fired a crossed the magneto speed in order to come up with a calculation of if accuracy..

I could test it against my old crony and see what the difference is but that still won't tell me if either one is accurate..

Another thing is the magneto should read faster than a crony 15 feet in front of the muzzle.. How much difference should there be over a 15 feet difference?

Any ideas as to how to test it.

Jeff

I don't normally have ranges that go to 2700m. That was a few weeks of my life. The solver was close enough though that wind was all we were dealing with and it took a couple of shots to hit an APC (the size of a medium UHaul truck). My most frequently used ranges go between 600m on the long end to 1000m if I'm on the KD. My very best range is shut down for another five years while they construct an aerial firing point (tell me, how does one construct a firing point for something that flies?) on the adjacent range.

I'm not an engineer so I'm not sure my calibration test for a Magneto-Speed is 100% sound but I think it would work. I would want a precise rifle and an optic I had tested for accuracy with a tall target test. Ideally, you have ammo velocity from a known load and another chrono to compare it to. I would want to use a bullet with a tested BC, not a calculated BC. I would shoot at least 10 rounds to get my AVG MV, ES, and SD. I would take that info and use my solver to shoot to the farthest range I had available to me and I would shoot a minimum of a 10 shot group to get mean center and measure the difference between predicted and actual drop and use my solver to get the MV.

I would think the difference in MV with the Magneto and sky screen would be calculated like any other residual velocity and will be dependent on the bullet. In programs like JBM you can select chrono distance from muzzle and it will give you actual MV in your drop chart. I would think if you did that with your sky screen to the MV you could compare it with your sky screen. Vice versa, measure MV with your Magneto and then plug numbers into your solver and make your distance interval 15 feet and see what it says velocity at chrono should be.

The only other way to calibrate would be having your loads pressure traced by a lab. You can also have bullets (if you make your own) Doppler tested so you have an accurate BC with which to do reverse engineering of your velocities based off of drop. Above all things, believe the bullet because they don't lie.

I would go about this differently at home but I'm up here testing some stuff and haven't had a chance to test the optic, and won't because engineers and analysts are running the program and I'm just shooting for them, but I was curious about the MV. Another gun chrono'd at 2660fps which is closer to my solver than to the Magneto-Speed. Everyone says the Magneto-Speed is spot on so I'm wondering if it is the optic. Feedback about optics is included in this test but we aren't given free rein to do what we want to evaluate the guns. The Army can make anything not fun.

Jeff,

I think your solution for checking chronos is as good as any I have heard. My solution is for a guy who has limited time and resources. Another possibility I have thought of for the MV discrepancy in my case is the distance the Magneto-Speed spear is from the bullet due to increased diameter.