It's all about angles!

Here we see crossers released from traps set at different distances from the shooter. When the clay is exactly in front of the shooter how far ahead should the aim be in order to hit it? Assuming that the clay is released at the same velocity from each trap, and it travels at exactly the same angle to the shooter (i.e. directly across his line of sight), then it is fairly obvious that the further away the clay is, the further ahead the shooter must aim. The key factor is the angle between the clay and the aiming point. This angle does not change with distance (*). So, it makes more sense to say "aim 5 degrees ahead of the clay" rather than "aim 6 feet ahead of the clay". The "6 feet" will obviously change depending on the distance away from the clay but the angle remains the same. Obviously you do not aim 6 feet ahead of the laser dot on the wall in front of you with DryFire - but you are shooting the same angular amount ahead - just as you do outdoors. For crossers this means that swing-through ("bum, belly, beak, bang") shooters adapt much quicker to DryFire than maintained lead shooters. For a swing-through shooter you match speed with the clay, swing through it and fire, no thought involved - either for the real thing or for DryFire, the speed of the target dictates your speed of swing. Maintained lead shooters need to estimate the lead required, they have to think, so it takes a little longer to adapt to DryFire. DryFire targets are projected onto a wall in front of you, much closer than on the range - unless you are in a Sports Hall or a Ballroom! However, the lead angle you must allow is exactly the same as on the range. For a fast crosser that lead angle will be much larger than for a slow quartering target flying away from you. What you learn to do with DryFire is exactly what you must do on the range to pulverise those clays. * In theory it does change slightly because both the clay and the shot are slowing down, but at the distances involved in clay shooting the two things tend to cancel each other out.

Vertical angles for trap

The amount of vertical movement when trap shooting is very small - as shown by this diagram for Olympic Trap.

To point directly at the trap the shooter would be pointing down by 6.7 degrees.

At the reference point (25m from the shooter and 4m above the ground) the shooter will be pointing up by 5.14 degrees.

So the total amount of vertical movement will be just more than 6.7 + 5.14 = 11.84 degrees.

Do your own calculations

To check that DryFire is starting a trap target at the right position follow this simple procedure.

• Check that your configuration settings are correct. If they are, when you use the pattern plate to calibrate your gun assembly the target dot should be exactly level with your eye position - i.e. your gun should be horizontal. If it is not, you have either set the configuration values incorrectly or you have entered an incorrect height for the shooter's eyes.
• With reference to the simple diagram above, work out the vertical difference between your eye height and the first point where the clay can be seen. In the case of an above-ground trap house this will be the height of the trap house. So, a shooter with an eye height of 1.7m and a trap house height of 0.8m would have a vertical difference of 0.9m.
• Check the horizontal distance between the shooting position and the point where the clay is first visible. For many disciplines this is about 15m.
• Calculate the down-angle as follows:

  Down angle = Atangent ( vertical difference / horizontal distance)

  In the above example this would be:

  Down angle = Atangent ( 0.9 / 15) = 3.43 degrees

  (Atangents can be found on any scientific calculator.)

Vertical angles for skeet

Even at its highest point, the clay on a Skeet layout is not very much above the horizontal as seen from the eye position of the shooter.

Let's take shooter facing a High House crosser from Stand 4.

To point directly at the High House trap the shooter would be pointing up by about 3.87 degrees.

At the crossing point, the Hoop, the shooter would be pointing up by 8.36 degrees.

So the total amount of vertical movement will be no more than 8.36 - 3.87 = 4.49 degrees.

Issues that may effect the amount of lead you see with DryFire

Accurate settings + accurate alignment = accurate targets + accurate shots

Accurate configuration and user settings

Double check all your configuration settings:

• Distance you are standing from the wall.
• Distance the simulator is from the wall (measured from the front of the camera head.)
• Height of the simulator from the floor (measured to the apertures on the camera head.)
• Distance the simulator is to your right. If you are standing behind it this should be "0".
• Length of wall to the left of the simulator.
• Length of wall to the left of the simulator.

Check your shooter height value. Click on Edit next to the shooter name. The height is the distance from the floor to your eye level - not to the top of your head.

Accurate alignment

Use the Pattern plate option from the Setup menu to do muzzle alignment. This should always be the first thing you do at the start of any shooting session. The Aligning your muzzle assembly section of the User Guide provides full details.

Testing lead

We have added a lead testing facility to the DryFire software (version 1.02F dated 9th January, 2004 onwards).

1. Double check your configuration settings and your muzzle alignment (see above).
2. Select Start lead test from the Setup menu.
3. Select the target you wish to test - Skeet 4 high followed by Skeet 4 low is recommended to try left and right targets.
4. Click on Start and call Pull in the normal way. The system will time-out after 10 seconds if you do not shoot - this is to prevent overheating of the laser.
5. When the target stops, shoot directly at it - just as for muzzle alignment.
6. You will see a miss shown on the screen. Make a note of how far ahead/behind you were. The amount you have missed is the amount of lead required at that point in the target's trajectory.
7. Now do exactly the same for the other target and record the result.
8. The two results will not be exactly the same because the two targets are not following exactly the same trajectory. However, the values should be fairly close together.

   The actual values you see will depend on the cartridge and other values you are using but typical miss-behind results for English Skeet Stand 4 might be: high: 0.85m and low: 0.92m.

9. Select Cancel lead test from the Setup menu to cancel lead testing and return to normal use.

Note: the target will stop a fraction of the way through the time of its flight - not the distance of its flight. See the next section if you wish to change this fraction.

Changing the DryFire .ini file

1. Close down the software.
2. Use Windows Notepad (select Windows Start, then Run and enter "Notepad") to find and edit the file called c:\program files\dryfire\dryfire.ini.
3. Find the line:

     Leadpoint=3
   

4. The value specified in Leadpoint defines the point at which the target will stop during its flight. A value of 3 will stop it 1/3 of the way through its flight time, a value of 4 will stop it 1/4 of the way etc.

   Don't forget that the clay is slowing down rapidly during its flight - it starts very quickly from the trap and ends by almost floating to the ground. So a value of 2 will stop it half way through its flight time but by then it will have gone a long way beyond its half-way distance.

   Hint: if you wish to do the test on Skeet 4 so that you can check left and right going targets, we recommend value of 4 for Leadpoint.

5. Save the file and run the DryFire software again.