Re: DTA 3000M + Long Range Shoot This Thursday!
you never mentioned what method was used to establish your dope , so some blanks were filled in...
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Since no program was mentioned in Nick’s report I ran some numbers to see how the predictions worked out at that extreme range.
DTA’s report yielded the following
Environmental (verified with Kestrel weather station)
Distance: 3040 Yards verified with vector IV (reliably ranges to 6KM)
Temperature: 13 to 17 (5 to 10 drop with wind chill)
Barometric Pressure: 30.3
Altitude: 5,446 ASL
Humidity: 46%
Bullet Flight Data
Velocity Remaining at Target: approx 850+ fps.
Time of Flight to Target: 6.5 second flight time.
Wind 6 mph (gusts to 10-12)
Elevation Adjustment Required: 40.8 MILS above 100 yard zero
Wind Hold range: 1 MIL to 2.5 MILS
Supersonic range in conditions: 2560 yards
Now, if you use the following input for all 3 programs:
MV= 3118 fps
BC – G1 = 0.890
DC = 0.500 (ColdBore 1.0)
BW = 352 gr
ZR = 100 yards
SH = 2.0 Inches
WD = 030º
WV= 9.0 Mph
Lat = 40ºN (aporx)
Az = 003º
you get these results from 3 programs. It’s important to note that I used, just for comparison purposes a calculated BC-G7 of 0.433 and since Litz’s program does not use BARO, the input Air Density was 0.07071 lb/ft³ which is the exactly the same as for using a BARO pressure.
Range = 3040 yards ( 2780 meters)
ColdBore 1.0 = 40.8 MRAD
JBM (with BC – G1) = 36.1 MRAD
JBM (with BC –G7) = 38.2 MRAD
Litz (with BC – G1) = 37.04 MRAD
Litz (with BC – G7) = 39.24 MRAD
As can be fully appreciated, NO TWEAKING at all was used in neither program.
Coriolis is basically nil since the target’s Az is almost North, otherwise at that distance, it could represent a major issue.
In regards to CB1 it’s important to note, that I used the ZR in METERS (90m) instead of yards, in order to go beyond the limit of 3000 yards, so effectively allowing the program to up the range’s upper limit to 3000 meters (3280.8 yards)…a little trick! So my Range for comparisons was 2780 meters. (3040 yards)
I like this kind of test because they allow me to teach the critical importance of Wind at extreme ranges, given the significant effect it has on the bullet’s drag…something that some LR students fail to see at shorter ranges.
Now, beyond the predictive huge differences and final “best overall prediction” that allows a real first hit, I think it’s a solid argument for your continuous statement on the G1 vs. G7 debate…and once again you are right on the money, what is important is the ballistics engine…not the Drag Function.</div></div>
I would be interesting to add what you used to get your numbers, even if it was more trial and error than using a program or some other method. If you can, actually shooting it is the best method, but a lot of people can't afford to send that many rounds downrange, especially with the big guns.
