Ballistics

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Need ballistics data but don't have a program?

You're in luck. Check out JBM's real-time interactive online ballistics calculator. It's very fast, very accurate, and it includes windage corrections and time-to-target data. Just plug in bullet weight, BC, muzzle velocity, wind speed and angle and it will plot bullet trajectories from 50 to 1000 yards for you. The JBM program has also recently been updated with actual G7 values based on field tests by Byran Litz. CLICK HERE for the latest JBM Trajectory Calculator. You can even print out customized Trajectory Cards with Click Values.



The first question we're asked about the most cartridge designs is "how fast will it shoot?" Of course the answer depends on bullet, powder, and barrel length, but here are some benchmarks for the 6BR case:

6BR Case Bullet Powder Barrel Ft/sec
Standard 80gr FB Fowler VV N-135 28" 3100
Standard 90gr Lapua Scenar VV N-540 Factory Load 26" 3031
Standard 105gr Berger LTB moly Norma 203-B Factory Load 26" 2789
Standard 107gr Sierra MK Varget 28" 2850


The key factors in calculating ballistics are bullet BC, bullet weight, muzzle velocity, and wind. Once you have this data in hand, you will need a mathematical program to determine what actually happens to the bullet once it leaves the muzzle. Click here to download free PointBlank Ballistics Software:

Free PointBlank Ballistics Program

Here a sample PointBlank screen with actual values is displayed.

A more sophisticated program, well-suited for VLDs, is the Pejsa Ballistics Spreadsheet. You will need Excel to run it. Right-click and "save as" to download here: Pejsa Ballistics.xls from JacksonRifles.com. If that link doesn't work, CLICK HERE. For field use, the spreadsheet prints a small MOA trajectory and windage table to stick on a gunstock. The spreadsheet will run on a WindowsCE or Psion hand-held computer so you can adjust for atmospheric conditions, wind speed, etc. in the field. For use with a rangefinder, the spreadsheet can calculate windage and elevation MOA for any particular range.

Related Article: Horizontal Wind Drift vs. Distance -- The "Rule of the Square"

Recommended Hardware

CED M2 Chronograph
Millenium CED M2 ChronographAt $189.00, the new CED M2 Chronograph offers the best performance you can get in a Chrono for under $400.00 (now that the Oehler 33/35 are no longer offered). It is more repeatable than lesser-priced brands in “less-than-ideal” light conditions, and the control unit is much easier to use than the “folding box” variety. Representing a significant upgrade over the previous CED “Millenium” model, the new M2 has more memory and can clock a wider range of bullet speeds–from 50 fps all the way to 7000 fps. The upgraded M2 will record velocities at much lower light levels than the previous Millennium chronograph. Included with the CED M2 are chronograph, sensors, cables, screen mounting bracket, USB computer cable and CED Data Collector software.

PACT Professional XP (Infrared)
The PACT Professional XP offers all the features we want in a Chronograph at an affordable price -- starting at just $229.00. The skyscreens are easy to set up and store compactly. The base unit has large, easy to use controls, and contains a built-in printer. Having an integrated printer is a major "plus factor" for the PACT compared to other chronographs currently for sale. The PACT features an upgraded sensor design that makes it more reliable and repeatable. New Glint Guard 2TM bullet detection system offers even greater accuracy and sensitivity in the widest range of light conditions. An enhanced PC interface lets you download your ballistic data to your computer and upload new bullets from your computer to your PACT chronograph. The optional IR system is worth every penny as it allows the unit to provide excellent results, even in complete darkness.

Oehler Ballistic Chronographs
Oehler ChronographsSadly the Oehler model 33 and 35P (with printer) chronographs are no longer in production. These are ultra-reliable units that work well in light conditions that cause problems with cheaper units. We have personally witnessed the superiority of an Oehler 35P, compared to a Shooting Chrony. Under bright,noon-time overhead light conditions, the Chrony produced an error every third or fourth shot and even when we got a recording, the number seemed off by 150 fps or more. Switching over to an Oehler 35p on the same benches, the errors disappeared and the velocity readings immediately moved into the reasonable, predicted range for our load and bullet. Better engineering and subcomponents explain why Oehlers work better that Chronys. Oehlers use focused beam lenses for less diffusion, plus a longer screen-spacing for greater precision and accuracy.

PVM-21 Infrared Chronograph
PVM-21 ChronographOehler's phasing-out of its Model 35 chronograph line has left a void in the market for high-grade chronographs. The new PVM-21 chronograph from Germany will fill that need. It has many advanced features and comes packaged with very sophisticated software.

With the PVM-21, which employs multiple infrared emitters, you can use the chrono in any light condition--indoors or outdoors. Tests of two PVMs set in parallel proved the units give extremely consistent results. Measuring a 55-grain .223-caliber bullet, two units showed an average variance of less than 1.5 fps on the shot by shot readings. Compared to an Oehler, the front and rear light sensors are placed fairly close together. With conventional engineering, longer spacing normally produces more accurate and reliable results. However, the PVM-21 employs a very high measuring frequency (16.0 Mhz) to provide excellent results even with compact dimensions. Additionally, the unit samples ambient light every 10 seconds allowing it to automatically adjust to changing light conditions. The PVM-21 features a 250-shot memory, and full PC-compatibilty via USB interface. Output can be displayed on a laptop PC, as well as the LCD readout on the PVM-21's display unit.

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