Hawke Ballistic Reticle Calculator - Second Edition (BRC2)

Welcome to the Hawke Ballistic Reticles Calculator (BRC) helpfile. BRC2 is a free tool designed to compliment the Hawke Specialised Reticles (SR6 and SR12), Hawke Multiple Aim Point reticles (MAP6 and MAP8), Crossbow reticles (Crossbow MAP, Crossbow SR, XB30, XB1 and XB1ir), Deer PASS SR and MAP and the 10x and 20x 1/2 Mil-Dot reticles. The BRC software will be updated to include new Hawke reticles as they become available. Please check the Hawke Optics website regularly for news and updates.

Introduction: The basic information that you'll need to install the BRC software and to get started with using it.

Installation: BRC makes very little demand on the host system. To run BRC, your system will need:

Operating System: MacOSX or any flavour of Windows for which a Java JRE is available. (i.e., all of the above.)Free Hard-disk space: 12 MB or moreDisplay: resolution 600 x 800 or better. A colour monitor is preferred but a monochrome device is usable. You will also need a printer on which to print the trajectory graph and/or reticles. Again, a colour printer is best but a monochrome printer will suffice.

The Least You Need To Know ...Using the Hawke BRC software is simple enough if you follow the basic procedure below. To achieve real accuracy you'll need to have some fundamental information to hand - Muzzle Velocity, Scope Height, Zero Range. Anyway, start-up BRC and ...

1) Select a Preset application from the Preset Menu. Choose an option that is close to (or the same as) your particular application. Each preset option has a number of values associated with it - automatically selected when you choose from the Preset list. If the reticle selected by the option of the preset menu is incorrect then you can change it by choosing another from the Reticule menu.

2) Save the setup as a custom application. Having selected a preset and (perhaps) an alternative reticule, save your work using the Save As ... option of the File menu. You'll be prompted to supply a suitable file name (or keep the default preset name) and the software will append a .brc2 extension before saving it to the hard-drive.

3) Make any necessary adjustments using the Data Input Bar. So far, so good. Now you can use the Data Input Bar to edit the preset values to match your actual values.

4) Save it again. The Save option on the File Menu should be accessible now (if not use the ‘Save As ...’ option instead) so click on it to save your finished work.

5) Print the Trajectory Graph. Make sure that your printer is connected and powered up and that you have suitable paper in your printer (A4 or US Letter). Right-click on the face of the graph and choose Print from the popup menu.

6) Print the Reticle/ScopeCap Images. After first ensuring that your printer is connected, powered up and has sufficient paper installed, right-click on the Reticle Panel and select Print from the popup menu and select the destination printer from the Select Printer dialogue.

7) Done. BRC can be closed in two ways; Select Quit from the File Menu or click on the Application Close button (Windows:top right-hand corner of the main panel, Mac:red marble at the top left-hand corner). In either of the above cases - if you've altered any of the values since you last saved the data - you'll be asked if you want to save the data (Yes), discard it (No) or cancel the exit request (Cancel).

BRC Elements: Detail of the various elements of the BRC software.

Title Bar:

Displays the current BRC2 status; version, preset/file currently in use and the maximize/minimize/exit controls (Mac version shown). An asterisk after the preset/file name indicates that one or more of the details (Muzzle Velocity, Ballistic Coefficient, Zero Range, Scope Height, Magnification or Reticle) has been changed.

Menu Bar:

The Main Menu bar giving access to the function groups:

File Menu:

Generic file operations:1) Open an existing BRC2 datafile,2) Save changes to the current BRC2 datafile (if the current file is unchanged then

the option is greyed-out as above),3) Save As ... to save the current file (or preset) under a different name.

The Windows implementation also carries an ‘Quit’ option (^Q) but, on the MAC implementation shown, said option is on the main system menu.

Reticles Menu:

Select from the range of Hawke reticles or, if an Internet connection is present, choose the ‘Hawke Reticle Information’ for more information.

Presets Menu:Select from the general categories: Air Power, Rim Fire, Centre Fire, Slugs and Sabots or Crossbow applications.

Select the appropriate Preset and click ‘OK’ to accept or ‘Cancel’ to cancel the operation. A preset can also be selected by double-clicking on it.Note that, if there are changes pending in the previous preset the user is asked if this should be saved as a file or, if BRC2 was perviously operating on a changed file, if those changes are to be saved before continuing.

Profiles Menu:

The Profiles menu only becomes visible when working with a saved (i.e., non-preset) file. Presets are already supplied with the appropriate ballistic profile (GA for air-gun applications, GL for Slugs and Sabots, G7 for 0.50 BMG (Lost River) and G1 for everything else.

Units Menu:

Choose Imperial (ft/s, yards, inches) or Metric (m/s, metres, centimetres) units.

Toolbox Menu:

Various utility functions for:1) Calculating the actual Ballistic Coefficient from Velocity Difference or Point-of-

Impact at distant range. See ‘Calculators’ below.2) Rangefinder display. The ‘Universal Rangefinder’ is always available - regardless

of the reticle selected - but the three specialised rangefinders can only be selected when the appropriate reticle is in use. See ‘Rangefinders’ below.

3) Displaying/hiding the Reticle and ScopeCap views. See below.4) Access to the Environmental, Colour Settings and BRC2 Utility functions.5) Additionally - if BRC2 is running on a Mac - an option exists to display the main

menu bar on the BRC2 application frame rather than on the top of the screen.

Help Menu:

A basic help menu comprising items to:1) show this helpfile,2) Send feedback via your local email client,3) visit the Hawke Sport Optics website and,4) check for updates.

The Windows implementation also carries an ‘About’ option (F2) but, on the MAC implementation shown, the ‘About’ option is on the main system menu.

Data Bar:

Enter specific data as per:Muzzle Velocity: in Imperial (ft/s) or Metric (m/s) units. Limits are 200 to 5000 ft/s.BC Value: Ballistic Coefficient values between 0.0050 and 2.000 are acceptable. Note that the BC values shown are always relative to the G1 profile - such as is published by ammunition manufacturers, etc. - regardless of the actual profile chosen.Scope Height: positive values less than (or equal to) 12.00 Inches are accepted.Zeroed Range: The minimum zero range is arbitrarily set at 10 Yards/Metres and the maximum depends on the other ballistic variables (i.e., that the proposed zero range is reachable giver the current Muzzle Velocity and Ballistic Coefficient).Magnification: depends on the specification of the selected reticle.

Banner:

If an Internet connection has been detected then clicking on the banner will start the system browser to point at the Hawke Sport Optics website.

Graph/Table Panel:

From the graph’s popup menu (right-click):

Point of Impact:Displays a graph of the Point-of-Impact v. the maximum ‘Reticle Range’ (or 2000 Yards/Metres which ever is the lesser).

Velocity:

Displays a graph of the relationship between instantaneous velocity (ft/s or m/s) and distance travelled (Yards or Metres).

Wind (lateral) Drift:

Displays a graph of projectile displacement (Inches or Centimetres) v. distance travelled (Yards or Metres) given the wind speed (MPH or km/h) and incident angle described in the ‘Environment’ applet below.

Elapsed Time:

A graph of elapsed time (Seconds) v. distance travelled (Yards or Metres).

Print Graph:prints the current graph to a selected printer. Inclusion of the background colour gradient (if any) is controlled by the ‘Show Gradient On printed Output’ flag in the ‘Colour Settings’ menu. See ‘Colour Settings’ below.

Save as JPG Image:saves the current graph as a .JPG image in the user’s ImageFiles directory.

... and from the Table panel ...

The table can be scrolled sideways (or the ‘splitter bar’ position dragged right or left to taste) to reveal ‘click’ values at various common scope calibrations (1/4moa, 1/8moa, etc.). Right-click to open the Table popup ...The display ‘step’ is set by selecting from the ‘Show every ...’ list and this same step value is used when the table is printed using the ‘Print Table’ option.‘Save as CSV file’ saves the current table - as well as the ballistic data - as a Comma Separated Value file suitable for analysis in common spreadsheet software.

Reticle View:

Displays the reticle aim-point/trajectory intercepts (in Yards or Metres depending on the ‘Units’ setting) for the current reticle and ballistic parameters.

The right-click popup-menu gives options for the reticle image to be printed or saved.The ‘Switch Rounding ON/OFF’ item ‘rounds’ the intercept ranges to the nearest 5 Yards/Metres - particularly useful for high-velocities and long-ranges. The ‘Reticle Lefthand SIde’ menu has options to (a) show the short ranges, (b) duplicate the long ranges or (c) show nothing on the lefthand side of the reticle. This selection is also repeated on the scope-cap.

The ‘Close’ item closes (hides) the reticle from view ... but it can be reinstated by using the Toolbox ‘Show/Hide Reticle’ menu item.

Currently, nineteen reticles are available:

SR6!! SR12! ! ! MAP 6

MAP 6a ! ! ! MAP 8! ! SR Pro

Xbow 1x32 SR Xbow SR Xbow MAP !

Xbow XB30! Xbow XB1 Xbow XB1 IR

WXB Evo FFP! WXB Illuminator WXB

Deer PASS SR Deer PASS MAP 10x / 20x ½ Mil-Dot

Scope Cap:

Alter the diameter of the printed Scope Cap (in Inches or mm) by adjusting the value in either text-box.The limits are 0.50 Inches (13 mm) to 6.00 inches (152 mm).

Right-click on the face of the Scope Cap image to open the popup menu. Options are:1) Print the current image to an attached printer. Inclusion of the background colour gradient (if any) is controlled by the ‘Show Gradient ... On printed Output’ flag in the ‘Colour Settings’ menu. See below).2) Save the Scope Cap as a JPG image or,3) Close the applet ... ... but it can be reinstated by using the Toolbox ‘Show/Hide Scope Cap’ menu item.

Calculators:

Calculate BC from Velocity Difference:

The applet starts with the Muzzle Velocity, Range and Velocity (@ Range) values inserted into the appropriate text-boxes. Alter these values to suit the specific circumstances of the test and click the ‘Calculate’ button to perform the BC calculation. As ever, the resulting BC value is computed relative to the G1 profile; the profile-specific BC value appearing in red if the current profile is not G1.

Note that is the preferred method of calculating BC although it does require the use of two matched chronographs (or one chronograph and many tests) and an accurate measure of range. Click ‘OK’ to accept the newly calculated BC value or ‘Cancel’ to ignore it.

Calculate BC from distant Point-of-Impact:

The applet starts with the relevant values inserted into the appropriate text-boxes. Alter these values to suit the specific circumstances of the test and click the ‘Calculate’ button to perform the BC calculation. As ever, the resulting BC value is computed relative to the G1 profile; the profile-specific BC value appearing in red if the current profile is not G1.Note that, because of its extreme sensitivity to errors in Range and POI measurements, this is not the preferred method of calculating

BC. It is however convenient in practical terms as long as the Target Range is significantly greater than the Zero Range (at least three times).Click ‘OK’ to accept the newly calculated BC value or ‘Cancel’ to ignore it.

Calculate BC from Elapsed time to target:The applet starts with the relevant values inserted into the appropriate text-boxes. Alter these values to suit the specific circumstances of the test and click the ‘Calculate’ button to perform the BC calculation. Depending on the measuring equipment to hand, the Time-to-Target or ‘Round Trip’ timings can be used; altering either changes the value of the other. As ever, the resulting BC value is computed relative to the G1 profile; the profile-specific BC value appearing in red if the current profile is not G1.

Note that, because of its extreme sensitivity to errors in Range and timing measurements, this is not the preferred method of calculating BC. It is however convenient in practical terms if the Time-to-Target (and the Target Range) are long enough to mitigate significant errors and suitable equipment is on hand.Click ‘OK’ to accept the newly calculated BC value or ‘Cancel’ to ignore it.

Rangefinders:

SR:

Displays the SR (Specialised Reticle) rangefinder found on the Hawke SR6 and SR12 reticles. Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification of the particular reticle (6.0x for SR6, 12.0x for SR12) whereas the selected Target size is retained and ‘remembered’ from earlier runs.Maximum and minimum magnifications are dictated by the particular reticle in use.Target sizes in the range 0.39 Inches (10mm) to 100.0 Inches (2540mm) are allowed.

The Right-click popup menu allows the rangefinder to be:1) printed,2) saved as a JPG image or3) closed. Re-open again via the Toolbox>Rangefinders>SR Rangefinder option.

SR Pro:

Displays the SR Pro rangefinder for use with the Hawke SR Pro reticle. Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification of 8.0x whereas the selected Target size is retained and ‘remembered’ from earlier runs.Maximum and minimum magnifications are 3x and 32x respectively.Target sizes in the range 0.39 Inches (10mm) to 1000.0 Inches (2540mm) are allowed.The right-click popup menu has the same options as the SR rangefinder above.

Deer PASS SR:

Displays the Deer PASS SR rangefinder. Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification (6.0x) whereas the selected Target size is retained and ‘remembered’ from earlier runs.Magnifications from 3.0x to 9.0x are allowed.The right-click popup menu has the same options as the SR rangefinder above.

Mil-Dot:

Displays the Mil-Dot rangefinder for use with the Hawke 10x and 20x 1/2 Mil-dot reticles. Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification of the particular reticle (10.0x and 20.0x respectively) whereas the selected Target size is retained and ‘remembered’ from earlier runs.Maximum and minimum magnifications are dictated by the particular reticle in use.Target sizes in the range 0.39 Inches (10mm) to 1000.0 Inches (2540mm) are allowed.The right-click popup menu has the same options as the SR rangefinder above.

MAP6a:Displays the MAP6a rangefinder for use with the Hawke MAP6a reticle.Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification (6.0x) whereas the selected Target size is retained and ‘remembered’ from earlier runs.Maximum and minimum magnifications are 3x and 32x respectively.Target sizes in the range 0.39 Inches (10mm) to 1000.0 Inches (2540mm) are allowed.The right-click popup menu has the same options as the SR rangefinder above.

Universal:

Always available, the Universal Rangefinder display a generic reticle image. Every time the applet is started (or ‘un-hidden’) the magnification defaults to the calibration magnification of the particular reticle but the selected Target size is retained and ‘remembered’ from earlier runs.Maximum and minimum magnifications are dictated by the particular reticle in use.Target sizes in the range 0.39 Inches (10mm) to 1000.0 Inches (2540mm) are allowed.The right-click popup menu has the same options as the SR rangefinder above.Utility Applets:

Environment:Set the ambient temperature (in ºC or ºF) and pressure (Inches Hg or mBar) in the appropriate text-boxes. If Atmospheric pressure is unknown then set the Altitude instead. Also set the wind speed (mph or km/h) and direction relative to the line of sight.Limits:Temperature: -20 to 60 ºC (-4 to 140 ºF )Pressure: 19.38 to 31.28 “Hg (655 to 1058 mBar)Altitude: -1000 to 10000 Ft. (-305 to 3048 m)Wind speed: 0 to 60 mph (0 to 96 km/h)The ‘Reset’ button sets the ambient temperature and pressure to ‘Normal’ conditions, i.e., 20 ºC/68 ºF, 29.95”Hg/1013 mBar and 0 Ft. The ‘OK’ button accepts any changes whereas the ‘Cancel’ button rejects them.

BRC2 Utility:

Options comprising:1) ‘Save changed Preset as file’: if the option is selected then, if the user abandons a Preset after making any changes, he is prompted to save the changed data as a file. If the option is unselected then such changes are simply ignored.2) ‘Automatically display appropriate rangefinder’: if checked the BRC2 displays the SR rangefinder if the SR6 or SR12 reticle is selected, the SR Pro rangefinder if the SR Pro reticle is selected, the Deer PASS SR rangefinder if the Deer PASS SR reticle is selected or the Mil-Dot rangefinder if the 10x or 20x Mil-Dot reticle is selected. This option is automatically cancelled if the user chooses

to close a rangefinder that has been automatically selected (by choosing the ‘Close’ option of the rangefinder’s popup menu or by selecting the rangefinder from the Toolbox menu when it is already visible).

3) ‘Show gradient on printed output’: prints any gradient if checked, not if unchecked.4) The textboxes for +/- increments (on the main page's Muzzle Velocity, BC, Zero

Range, Scope Height and Magnification textboxes) initially hold the default values but can be adjusted to whatever sensible increment is required. Simply edit the values as required and click on the 'OK' button to adopt them.

5) The 'Reset' button resets the increment values to the initial (default) state as above.

The ‘OK’ button accepts any changes whereas the ‘Cancel’ button rejects them.

Colour Settings:A gradient consists of a controlled change of colour between a ‘Top’ colour and a ‘Bottom’ colour. Select the colour to be changed (Top or Bottom colour) then pass the mouse pointer over the colour swatch and left-click when the over the appropriate colour.The ‘Show Intercept lines in colour’ check-box draws the intercept lines on the main POI graph in colour if checked - or to be drawn in mid-grey if unchecked. The ‘Mono’ button sets the top and bottom gradient colours to

white and deselects the ‘Show Intercept lines in colour’ option.The Gradient of the particular components can be set using the array of check-boxes to the right of the applet.

About:

The BRC2 About applet gives general information regarding the product and its capabilities.Scrolling the text-area will reveal details about the product, registered user, local machine (O/S, version, etc.) and the location of the DataFiles, ImageFiles and CSVFiles created by the user (as well as enumerating/listing same).

Clicking on the ‘OK’ button closes the applet.

Glossary

Apogee! The highest point in the pellet's/bullet's trajectory. Sometimes known as the Zenith ! or Peak.

Ballistic Coefficient (BC)A measure of aerodynamic efficiency. Primarily varying with the projectile’s sectional density, the BC value is altered to some extent by its shape (or form). BC values - regardless of their actual Ballistic Profile - are expressed in terms of the G1 profile within the BRC2 software. The units of the Ballistic Coefficient are the same as Sectional Density (Lbf/in²) although these are rarely stated explicitly.

Ballistic ProfileThe characteristic curve of Velocity v. Drag Coefficient for a particular projectile form. For various reasons, the G1 profile is generally used for comparison purposes although assuming G1 for every projectile shape may not give optimized results.

Exterior Ballistics! The study of the projectile in flight between muzzle and target.

Interior Ballistics! The study of the projectile while still restrained by the barrel.

Line of Sight (LOS)! The imaginary line between the scope and target (POA)

Line of Departure (LOD)! The imaginary line along which a projectile first emerges from the muzzle.

Muzzle Velocity (MV)The velocity of a projectile (pellet, bullet or arrow) as it emerges from the muzzle. Measured as Feet per second (Ft/s) or Metres per second (m/s).

Scope Height (SH)The scope height is the distance between the line-of-sight and the line-of-departure measured at the muzzle, i.e., where the trajectory begins’

Terminal Ballistics! The study of the projectile after it has hit the target.

Trajectory! The arc of a projectile through the air from muzzle to target.

Point Of Aim (POA)! The intended impact point on a target.

Point Of Impact (POI)The point on the target where the pellet/bullet strikes or, in this context, the vertical distance between the point of impact and the point of aim.

Zero(ed) Range (ZR)The point at which the pellet/bullet/arrow crosses the Line of Sight. In most cases there will be two such points; confusingly, the furthest from the muzzle is usually called the Primary Zeroed Range whilst the nearer point is often called the Secondary Zeroed Range. If there is only one point then this, by definition, corresponds to the point where the Apogee (above) is zero (i.e., lies on the LOS).

BRC2Help,V2.0.7, 30/11/13