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Getting into Field Target Shooting Part 7

Getting into Field Target Shooting Part 7

Side wheel focus has now become the norm on FT scopes. This month, I’ll go through the set-up process and a few techniques that will help get you started in the important skill of rangefinding! To accurately range a target at 55yds, you need at least 30 to 32x magnification at its highest power. 50X is not uncommon these days but has drawbacks too. Having made your choice, it has to be marked up for ranging and a decision made on what technique to use that will provide consistent and accurate results. Using the side focus for ranging is a skill on par with trigger control and should not be under-estimated. Here’s what you will need:

  • A tape measure that reads out to 55yds (165ft)
  • A target (preferably black and white)
  • A good pen (I recommend a CD marker pen)
  • Masking tape

You will also need an adjustable pointer (recommended) or a fixed reference point on the scope. Both will be needed if an expander (shark fin) wheel is used. These are not circular and negate the need to use a huge round wheel of which over 50% remains unused. The expander extends only in the area most used and is less cumbersome.

It is important to pick a reasonable day, without direct sunlight reflecting from the target or into the objective lens. First, apply a strip of masking tape to the wheel, ensuring that it extends from the closest possible focus point to 2/3rds of its circumference. This will ensure that there is enough room for marking points from minimum to maximum range.

With an expander, the wheel needs to be positioned on the scope with the bottom edge of the fin approximately ¾” below the pointer. This is to keep the 30 to 55yd markings on the extended portion of the expander. This is where the second pointer comes into play, as it is used on the small portion of the shark fin!

Down range

Set up the target and layout the tape, then take up a position at the point that corresponds with 35yds. Experience says that this is the optimum range to use for calibration. Your preferred zero can be selected after all markings are finished. Ensure that the front edge of the objective lens corresponds with the exact distance to the target!

You are now ready to provisionally mark the masking tape. This is an important mark, as all subsequent ones are related to it and as the distance increases, the gaps between the yardage gets smaller, so any error here will be magnified at maximum ranges. Depending on your scope, the focus wheel will be ‘clockwise’ or ‘anti-clockwise’. The former goes from maximum to minimum range and the latter minimum to maximum.

Position and repeatability is the key to best results! Ideally, all adjustments should be done from the FT sitting position. Another consideration at this stage is whether a glove will be used or not. It will give a different feel to the operation and can alter results.

My method

Set the magnification; ideally the scope needs to be at least 32x to be effective at 55yds. Why? Because I believe that to be the best all round setting that can be used in all situations. Using varying power settings will result in varying results. 50x will not allow as much light into the scope and can be tricky in dark and shaded spots. The only answer is to turn down the magnification and this will alter the way the focus snaps in and out and add an element of doubt. Remember that this setting is for ranging and the actual shooting magnification can be whatever you decide on!

Starting at the far range of the focus, smoothly turn the wheel while viewing the out of focus target. It will gradually become clear and then start to blur again as it goes past that sweet spot and starts to focus the foreground. At this point STOP and gradually move back to the sweet spot then STOP and check the wheel position. All this is done in one smooth motion in the time it takes to slowly say: “Forward, through, and back”!

Mark and check

Note the position of the wheel in relation to your fixed reference mark, or adjustable pointer, and mark a dot level with it. Now repeat the ranging process to confirm that it lines up with the fixed reference. Repeat a few times, taking care not to stare through the scope for any longer than it takes to perform the operation. The eye is adept at making small corrections and can start making its own adjustments that could lead to inconsistencies. Once satisfied, draw a horizontal line across the width of the wheel at that point.

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This method can be reversed by starting at the near range and going past the target distance before returning to the focus point. However, mixing the methods will usually result in two different marks! Why?

Depth of field

Definition: The zone of acceptable sharpness in front and behind the object on which the lens is focused. It extends approx. 1/3rd in front of and 2/3rds behind. This helps to explain why the two methods can have different results. For me; starting from distance, then coming in, through and back, utilises the shortest depth of field, with the sight picture ‘snapping in’ more precisely.

Once you are happy with the initial zero mark, the other main markings can be provisionally set by moving back in 5yds increments until all the ranges from 35 to 55yds are marked. As the distance increases the markings get closer together and a large diameter wheel or fin will differentiate easily between 50 and 55yds. Take extra care over these two markings, as a 2 or three yard differential at these ranges will probably result in a miss!

An additional mark can be set between each of the above ranges that will give a 2.5yd increment from 35 to 55yds if you so wish. I leave the space clear and just use a visual check for the in between distances.

Mind the gap

Here are some examples of the sort of gaps you can expect between 35 and 55yds using a 5” wheel or fin: 35 and 40yds - 7/16”, 40 and 45yds - ¼”, 45 and 50yds - 3/16” and 50 and 55yds - 1/8”. These spacings can differ depending on the scope, in this case a Nikko Diamond ‘Big 60’.

You now start working down and 30yds is the next distance. If you are using the expander/fin you will find that the extended portion that corresponds with the main pointer will just accommodate 30yds. Anything under will require a separate reference pointer, as it will now fall onto the smaller diameter portion of the wheel. Usually, the rear scope mount can be marked with a white dot, which does the job!

From 20yds down, the shallow depth of field will allow you to mark the wheel in one-yard intervals. This is every bit as important as the longer ranges, particularly if you are using high mounts. The pellet will be climbing steeply below this distance and a 15mm hit zone requires accuracy within a yard.

Getting down

It should be possible to mark the wheel down to 10yds, but this is not always the case. Some makes only focus down to 15 or 20yds and in this case a 50ft adapter lens can be attached to the objective, giving it a focus range of around 5 to 20yds. The scope wheel is marked off in the same way as above, with the shorter distances in-between the main ‘open objective’ focus marks. It causes a lot of ‘clutter’ on the range wheel, but deals effectively with the problem of close range-finding.

The minimum for FT is now 10 yards and can prove tricky, particularly the ones with tiny hit zones. The magnification ring can be used to judge these if the scope is just short of being clear. Set the focus wheel to its minimum and while viewing the blurred target, gradually turn the magnification down from high towards its lowest setting. As soon as the target becomes clear, stop and note the setting. A 12yd target may become clear at around 15x but an 10yd one will still be out of focus requiring further reduction in power to 10x. It all depends on what you are using!

Once the wheel is marked provisionally, it needs to be re-checked and used until you are completely satisfied with all the positions. Remember to use the same technique, gloved/ ungloved. Only then is it time to think about marking the wheel with proper numbers and lines that will put the finishing touches to all your hard work.

Regular checks can be performed using the initial zero and the longest distance points. Provided the markings are accurate, any re-calibration required will be linear throughout the scale and easily corrected using the adjustable pointer. With practice, it should be possible to accurately read ranges every yard up to 20 and every 2 ½ yds from 20 to 55yds!

Good shooting
Terry Almond

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