WildcatBullet 338 cal 350 gr elevation at 2000 yards ???

[DANTEC]

Matt

from pure metrology I agree than 0.25 moa from scope turret is a bit " un accurate " measurement system BUT that a usefull way to compare and get a delta or gain valiue between two things

300 SMK a well know bullet wich is define by 6DOF equation fly so able to receheck with several methods
and
the ??? datas of the new wildcats bullets

so between to do nothing and speak hollow , making a first computation is not to bad , and far better than to enter in dream story as 408 balanced fly theory proven with unreachable dopller datas

often logic and simples methods are better than mystery and Harry Potter respices

good shooting

DAN TEC

 

[abinok]

Like dantec said,
Its not the most reliable way to generate data, but it does allow data to be compared to some extent, especially when comapring it to a well modeled bullet like the 300gr SMK.
Like dantec said, its better to do a rough comparison than to just set around and dream about it. Hopefully when Brent gets some 350s over the chronys, we will have some hard numbers to go by.

HEY DANTAC, I just showed your modified "california legal" 50 BMG to a friend, I never can remember the name of it, but he is convinced you are a genius!

 

[Brent]

Okay, I'll throw one more stick in the spokes here: The BC for the 300gr SMK in my tests does not agree with the number stated here... It was something in the order of .787 or there abouts at about 3000 fps. I'll see if I can find what I came up with in the tests using the 43.

Along the lines of what Matt said, I think drops compared from the same rifle/scope combo is a much better way of comparing the two bullets.

GG would do well to set down with his rig and determine what his click values truly run throughout the range of adjustment. The distance multiplies the error and in his case (1500-2000 yards), it could be very frustrating to find out that it is a slight turret miscalibration keeping the first shot predictability in various conditions elusive.

I've got a 32" barreled 10 twist 338/378 Wby to compare the 300gr SMK and 350gr WC. Not too much longer and we should be able to get set up at 500 yards with the chronos for some testing.

I hope the 350's group well enough to keep them directly over the chrono at 500 yards.

Does Richard make any .510" bullets?

 

[Brent]

338/378 Wby 4.1" OAL 300gr SMK, 32" Pac-Nor bbl.

This is only a 100 yard test and might prove a little different BC numbers at 300 yards or more. The measured distance to the acoustic target is very critical and BC's can be off considerably if not measured to within 1/10 of a foot. Obviously because of this, the further away it is placed, the less error there will be with an identical distance measurement error.

Next time I'll test with two chronos, which I have not done with the 300gr SMK.

A little info on what you see here and how it works:
The acoustic target uses three acoustic microphones, each one located on a point of the triangle frame. The mach wave from the passing bullet triggers each "stop" sensor. The start screen located on the chrono rail starts the clock. With a starting and stoping point, the time of flight to target(TOF2T) is measured. With a known MV, and TOF, the downrange velocity (Vel-T) and BC can thus be calculated.

TOF is also captured in another section for each individual microphone in order to triangulate the exact bullets path/location through the three sensors.

With the use of a chamber attached strain gage peak pressure (Peak) is also calculated.

You can see the difference here is, the acoustic target relies on TOF and MV to determine BC and Vel-T, where two chronos know the exact MV and Vel-T to calculate the BC. The distance measurement of two chronos is thus much more forgiving and not nearly as critical.

 

[Matt27]

Brent

I believe Richards does make 50cal bullets.
Shoot him an email

 

[goodgrouper]

[ QUOTE ]
GG would do well to set down with his rig and determine what his click values truly run throughout the range of adjustment.

[/ QUOTE ]

Yes, I suppose I could, but in all reality, testing bc with this back door approach at 2000 yards is just plain inaccurate anyway.

I could tell you how many clicks it took to get to 2k today, and then tomorrow it would take more or maybe less. If the wind switches from tail to head and it just added another 3 minutes to the drop. That is just too much interference to accurately calculate anything. The only real way to do it is with a Model 43 or a Doppler radar. This thing that Dantec is supposedly running is just for kicks and giggles. Are you done with it Dantec?

 

[DANTEC]

I not agree with you

if you plan to measure ( metrolgy operation and not pretty display on a computer because display on a computer is NOT a true thing EXCEPT after to have check all step of the measure from adta aquisition , to A/D conversion to final sofware equation checking and software programming )
a velocity with a oehler 43 ( sound target ) you perhaps need to be sure of all atmospheric parameters because speed of the sound vary with air density
you need to carefully calibrate your sound target system for the velocity you want to catch because subsonic fly noise , transonic fly noise , supersonic fly is not the same
you need to calibrate to your sound target for bullet location and be sure than your measurement map give you the same reading data , so at 2000 yards where you shoot in your target ???
you need too to carefully check your instrumental velocity to the bullet velocity ( not really the same if you plan to reach the real accuracy in measurement )

now on my idea to compare things to things

you shoot at a know distance with a know bullet ( BC ) launch at a know velocity in a know atmospheric conditions
you get a elevation ( on turret ) to reach your target
all of that are true fact , parameters as tail wind ... can be forget )
you do another trails with another bullet
change is only bullet and velocity but you can record all parameters EXCEPT bullet BC so you can by computation get an good idea of the bc of the bullet you have shoot

and by computation you can find you BC bullet IF all your fly is in true supersonic velocity to stay in the straight aera of your drag curve and avoid transonic aera

as Dopller story/myth /dream/myhery

Doppler is costly to use that a fact
Dopler data need to be post compute by a software as PRODAS ( another $$$$$$ piece of equipement ) to get BC data and usefull data because raught dopller data is just a numerical file without any use without post computing
Dopler data need to be use ONLY by qualified engineer to not spread internet with dummy value or magic results

so to make a conclusion logic and engineering view of problem can allow to make pretty accurate thing without million of $ of equipement

as equipment I use I use impact target ( piezo sensor and measure time of fly between the muzzle and my impact , transmision time is calibrated with a 100 Mhz pulse generator to measure how much time my impact target signal ( during data acquisition and after data aquisition ) take to come back to my computer

I have more fun to make field instrumention than to make noise with costly shinny rifle and I am interesting first by true enegineering speaking .

good shooting

DAN TEC

 

[Richard338]

Dantec,
How easy (and expensive) is it to build your time of flight system? Can you provide some more details?

 

[Brent]

Dantac,

I know the Oehler chrono's I have do work very well, and the acoustic target is a direct match to an overlayed paper target when set up properly, so it can't be that far off given the speed of sound variations in different MET conditions. I do agree that there is a certain amount that one relies upon in the software calculations etc in order to end up with the BC number it comes up with.

In my mind, the two chrono setup for measuring BC's is probably the most accurate, but then we still rely on software calculations to give us the BC value from the velocity loss over a given distance there too. It don't really matter who's ballistic program you use to perform these calculations with you velocity data, as all of them that I have used come up with nearly identical BC numbers, so they must be using the same formula, and all of them must be right, OR... all be wrong.

I appreciate the engineering behind this stuff and it is interesting, mostly when I can see its practical application to helping me hold smaller groups, hold POI to POA, better trajectory predictions etc, etc, etc. It's really a mean to an end for me, and is why it's so interesting I guess.



[ QUOTE ]
as equipment I use I use impact target ( piezo sensor and measure time of fly between the muzzle and my impact , transmision time is calibrated with a 100 Mhz pulse generator to measure how much time my impact target signal ( during data acquisition and after data aquisition ) take to come back to my computer



[/ QUOTE ]

I'll try to follow you if you have time to fully explain what you know about this some time. Sounds interesting and this is the first time I've heard of this.

 

[DANTEC]

ok more informations

first some tipes on the basics of instrumentation /measurement equipement

calibration : for every thing /every stuff you use you need to calibrate
exmple
a thermometer probe will be dip in a bath od melded ice to check the zeo ( temperature of melted ice in water is a perfect know temperature ) and dip after in boiling water ( same perefcet know temerature , with possible correction with atmospheric pressure I agree ..)

so a chrono need to be calibrated with know velocity ammo as realmil specs ammo and/or twin chrono set up ( the second chrono will a be a lac quality one )

resoluation if you want/nedd to measure a physical thing the accuracy of your instrument need to be 1/10 of the lowest step you want measure
to check one inch you need a instrument accurate at 1/10 minimum
repetability ; you need to check if if you make string of same emasure you get the same result and that step by step if you use a sevreal stage electronic device and software too

after these points od details but very important to not measure anything with anything

as set up I use to make accurate velocity / TOF measurement

I use a counter timer ( not a cheap chinese /taiwan look a like ) a but HP 5334A or a 5335A these xcounter timer can reach 2 nanosecond on 1 event ( burst mode )
to trigger these trigger I use a
a first trigger near th emuzlle made with microphone and a amplifier/trigger interface to get a logic signal and start the HP5334A so the counter timet start to count

to stop it I use a pezo disk glue on a pannel ( rest of the target , when bullet hit the traget that create a vibration and the pezo disq generate a tension to command a electronic device to stop the couneter

main difficult thing is to find ( or know the time that your trigger signal ) make to come back from 600 yards , to measure this signal I generate with a pulse genrator a pulse at a know frequency in the wire - short range under 150 yards ) or fiber optic over 150 and up to 600 yards and check with a oscilloscope the time of ( delay ) of signal bteween each end of the wire or the optic fiber
so I can get a resulat as

( T(0) as staring time + T ( Imp ) display on the couner ) - time of signal in the wire = TOF

by and with a simalr equipement I can fit two panesl with piezo at 1000 yards and check velocity of th ebullet at 1000 yards or evne 1600 yards but I need to let my couneter timer at 1000 or 1600 yards or I can ( I works on ) use a RS232 radio ( wireless ) communication ports to control my counter timer at 1000 yards and read display on my laptop

all hardware can be made with surplus stuff purchase on Ebay
a HP5334a / HP5335a , Racal or a Solartron cost around as 150 USD to 200 USD
and home made PCB interface is not very costly
pulse generator on Ebay cost 200 USD
a 100 Mhz oscilloscope cost 150 USD or you can purchase a 100 Mhz with memory and use it for strain gage pressure system too

even if you add a small generator ( Honda brand with inverter ) toatl cost is not amazing at all

good shooting

DAN TEC

 

[goodgrouper]

Or you could just buy a Kestrel hand-held, two Oehler 35's, and/or a Model 43 and be done. /ubbthreads/images/graemlins/grin.gif

 

[ricka0]

I see DANTEC has lots of posts but I haven't seem him post lately. DANTEC is a good guy - as you can see from France. I've found that it's worth the extra effort to read his posts. I sent him over here for more info on Ultra Long Range Shooting.

 

[ricka0]

[ QUOTE ]
[ QUOTE ]
GG would do well to set down with his rig and determine what his click values truly run throughout the range of adjustment.

[/ QUOTE ]

Yes, I suppose I could, but in all reality, testing bc with this back door approach at 2000 yards is just plain inaccurate anyway.


[/ QUOTE ]

Everyone should do the scope vertical test anyway to verify their scope is plumb. While you are at it, set up a 12' 4x4 at 200 or 400 yards and a target. Then dial up 1 MOA windage, shoot, another MOA shoot, etc. You better get a vertical line or your scope is not plumb. It's then ez to measure exactly how much MOA you get for each click.

The thing I learned after extensive debating with the tactical expert Dean Michaels on the Coriolis effect (much smaller than the variation you get from scope clicks to actual MOA (dean right, ricka wrong) was [ QUOTE ]
Manage the events, and work the problem.

[/ QUOTE ]

excellent Scope Level info

 

[ricka0]

[ QUOTE ]

In my mind, the two chrono setup for measuring BC's is probably the most accurate,


[/ QUOTE ]

I agree for distances up to 300 yards.
Problem is you can't really use a chrono at 2,000 or even 1,000 yards or your going to take it out.

Using a pair of chrono's, say at 100 and 400 yards the measuring drop at 2,000 yards may be the best/cheap way of estimating the BC at 2,000 yards. If you measure temp, press, humidity, etc – you should be able to get some reproducible results.